Excellent video! Somehow you manage to capture the majesty of flying in a way that I'm never able to.
I've come close to putting the skis on a half dozen times this winter, but ever time I'm glad that I didn't, because the snow has rarely gotten too deep for wheel-flying, and every time I would've had to take them off a few days later once all the snow melted at my home base.
Roll-out on landing can vary from pretty much the same as on pavement (a few hundred feet), with good brake effectiveness (to the point both differential braking and tailwheel steering work fine), to 1000 feet or more with only aerodynamic steering, sometimes varying dramatically from day to day.
Some people choose to land into the wind, but I'm so paranoid about running into shore that I'll often land at least partially cross-wind to give myself more room for error. Just a few weeks ago I was landing on a course that he been set up for snowmobile races and was using the end-markers as references. On Saturday I landed westbound and only used 1/3 of the marked track - on Sunday I went back and landed to the east, and rolled right past the end because I couldn't slow down at all. The difference? Maybe 5 knots less wind, and the last inch or so of crusty snow had melted, leaving bare ice.
Cross-wind landings on ice or thin snow are way easier than on pavement - you can fly a crab all the way through touchdown, and then hold the crab in place all through your rollout. Years ago, I did my first solo in a 152 on a completely ice-covered runway at the not-very-well-maintained airport where I learned to fly - even then I was amazed at how much easier it is to land on ice than pavement. Yes, you still have to worry about running off the end of the runway (easy enough to manage when the runway is long), but most of the concerns about alignment go away. I won't say the chance of ground-looping is zero because that seem like inviting fate, but, well, for me it feels like all of the challenge in tailwheel flying has been eliminated, to the point where I find myself landing like crap when I get back on pavement, with lots of chirps and squawks and darting around because I get sloppy about keeping my heading and ground track lined up perfectly at touchdown, and don't have a good feel for the crossover between tailwheel and rudder steering.
I've been experimenting with using a blast of power and full rudder to spin the plane around so I'm facing backwards, then using power as "reverse-thrust" to decelerate (the aviation equivalent of a Rockford?), but it's not a technique I'd recommend trying at speed yet - I've only done it at taxi speeds. If you think a tailwheel aircraft is unstable when rolling forwards, imagine what it is like in reverse!
The "glassy water" hazards are real, and I've been bitten by them before, touching down unexpectedly a few seconds before I planned on, or having to really focus on off-to-the-side landmarks for my height references (that was on snow, at my home airstrip, on an overcast day with really flat light). Fortunately I haven't broken anything that way, but the momentary loss of height awareness is terrifying and definitely keeps me from going out to play sometimes. Lighting conditions matter a ton, as bad light can make it impossible to see hazards on the ground. As the sun is typically low in the sky this time of year, lighting can vary a ton from direction to direction, and sometimes I'll choose to land slightly downwind so I can better see the hazards, rather than into-the-wind if it means very flat lighting.
Hazards include the aforementioned ice fishing holes, plus snow drifts (which are sometimes saw-tooth shaped and very abrupt when hit in the wrong direction, even if only an inch or two high, especially if you are crabbed or sliding sideways when you hit them (DON'T DO THIS!)), cracks in the ice, pressure ridges, frozen ruts from ATV and snowmobile tracks, tree stumps, and pretty much anything else you can imagine, plus many things you can't. The point features like ice fishing holes are usually fairly easy to steer around, assuming there aren't too many of them clustered together, but the linear features take a lot of planning. Also keep an eye out for power lines - there are two in the area that this video was filmed that you could easily hit if you were to make a wrong turn and not realize it.
I'll usually do a pass at ~200 feet to scope out the area, then another pass at ~10 feet, offset ~20 feet to the side from my intended landing zone. Depending on the lighting and the direction of the snow drifting, I'll often do one pass in each direction, to make sure there isn't anything that is only visible in one direction. Even on fairly featureless lakes, I try to pick the exact point I'm going to touch down, because it's much easier to avoid obstacles that you have noticed ahead of time and are anticipating rather than discovering them as you roll towards them. It's easiest if I can pick out a landmark like an ice fishing hole or a barrel or piece of debris on the ice, or even a feature in a snowmobile track, or something like "just after I cross that long diagonal crack, 20 feet to the right of that shiny bump". Features like that also make for nice height references over completely a barren surface. If I have any doubts about the snow depth I'll probably just stay away, though even when I'm confident I'll often still make a power-on gentle-wheel-drag landing to feel it out, mostly just to learn how it feels like in case I actually need to use that technique to assess the depth some day. It's not something I'd feel confident in at this point. The wheel-drags are also useful for assessing how smooth it is - especially after there has been some drifting or vehicle activity, it can get really rough - probably safe to land on in necessary but hard on the airplane - so a pass to feel out how smooth it is can be useful in deciding to skip a place entirely (that's what some of the really low flying in the video was showing - just creeping lower an inch at a time to see how it smooth it feels - "patchy snow over ice" like that can range from "imperceptible bumps" to "feels like you're landing on a row of speedbumps"). My "comfortable depth limit" seems to be around 2-3 inches of snow, and it depends a lot on the character of the snow (soft powder is good hard crusty is bad), so it's really tough to assess from the air, even when you can see bare patches.
Anyway, I'm by no means an expert on lake operations (~30 hours and ~100 landings on skis, maybe half that many on wheels; all in one area of Wisconsin), but I've been doing it a lot lately and thought people might appreciate my comments.