My take is they all look good on video.
Given the little that we see, it's likely we can't make solid judgments based on video. However, I definitely form preferences based on the videos, and occasionally I feel like there is a rationale for these preferences -- especially when it comes to pitchers' deliveries. (For example, I like Brackman's and Aumont's deliveries quite a bit better than Beavan's, if we're talking giant righthanders ranked in the top 20). Ahren's swing just look quick to me, especially from the right side, and I put a premium on his being able to take up switch hitting successfully.
Again, I don't put a lot of stock in a difference of 20 places in a BA list. These kids are developing rapidly, and they came into the season ranked on information from a year ago, which may have been based on several reports or relatively few. Within a pretty broad stratum, I guess I'd give more credence to whether a prospect is rising or falling.