Personally, I watch these videos always looking for the "surprising." I don't think you can get much value out of limited reps and drills and such. But you do get to see things that change perceptions.
Last year, we saw Tuitt grossly overweight, Niklas make an absurd one-handed catch, and Corey Robinson catch everything in his area code. Before that I had no idea Tuitt was still going to be feeling the effects of injuries, that Niklas had those kinds of ball skills, or that Corey Robinson had that kind of absurd catching radius.
The biggest thing so far this year is Luatua's physically imposing nature. Makes you realize why he was the #1 TE for such a long time. He lost his ranking because 1) he measured out shorter than listed at camps so people knocked him for not having elite frame 2) he's not a WR-listed-as-TE that is going to show out offensively at camps/all-star games 3) people questioned his demeanor and football motivation.
Towards 1 and 2, he may not have elite height but he sure seems capable of battling in-line or dominating in an h-back role... and we have plenty of guys to be pass catchers first, blockers second. Towards 3, only time will tell but I haven't heard anything negative yet.
It's stupid to overstate his potential impact based on a couple clips but there is no denying that he, at minimum, looks the part.