Just my opinion but if a coach needs video to judge a player then you don’t have a very good coach. A coach should be able to sus out technical skills and how they play in scrimmages in fairly short order. The scrimmage with the new team also shows how they fit in with that team and environment vs any number of factors that might not be the same with their previous team.I think that's a good idea.
But I doubt coaches will take the time? I guess the dedicated ones really willing to make improvements on the team will.
On the other hand, maybe tryouts should include some element of full sized scrimmages?
Put kids in whatever they think is their best position is. You can tell within 10 minutes their level vs your current defenders.
Also I am of the approach that a coach shouldn’t take a player unless it is clear upgrade to the roster. Although I know the big clubs differ in this approach for $$ and winning reasons.