I'm personally not fond of that idea.
If it is just to promote the levels, then the solutions of the levels should not be shown as otherwise the whole point of the level is gone when watching the video. (That's why I haven't watched Lacktardo's or the few of BulletRide's videos). It only takes like a minute to download and open a levelset to have a glance at it, so I just don't think it is necessary. Videos only take a lot of space even if on YouTube.
And also for showing solutions, Lemmix allows for recording demos which are a lot smaller than videos (same applies for Lemmini I think); these recordings are not in the low video quality, you can play them in fast forward and also take over playing at any time, videos just don't allow for that.
