I've watched that video of course, though muted, because bias against Hamilton's adversary was very high last year and it's insane this year (it's easier when it's not his team mate obviously) - not only by SkyF1, but also by most of the (British) motorsport media.
So when you watch it muted and base your opinion on what you see and not what somebody else is telling you that you see, you see pretty much the same thing as was visible on Grosjean's on board - Stroll suddenly changed direction relative to the corner's line. As I posted screenshots from Seb's on board before, I'm not going to do that again as we are past the moot point, he kept his line relative to the corner at all times and hadn't moved his steering wheel as well. If somebody can present an argument that states contrary, I'd be happy to accept it - though, in all honesty, I'm pretty sure that such argument would have popped up by now.
It's a silly incident, with potentially huge consequences on championship battle, that underlines what is pretty much a trend now - younger drivers don't pay enough attention to their surroundings and FIA don't mean to do anything about it even though it is interfering with other driver's races badly (talking also about Ocon and Max here, not just Stroll). Having been their age just a few years ago, I'm starting to think they literally can't focus on so many things all the time during the weekend, as that level of focus comes with age. This is very common with motorcycle racers, in Moto3 fantastic drivers often slump in form when they stop trusting themselves and their bike - which is a consequence of loosing focus on racing when you have girlfriend issues and whatnot.