I use draft breakdown. It generally gives you enough to form a basic opinion, and if you can't find tape on a player you can always find tape on another player and watch the matchup, like tj watt had almost nothing so I was watching OL film that he played against.
Something I always like to do is watch a few highlights before I watch film, I wanna see a player at his best before I see all the inbetweens, it helps you get an idea of the players niche and helps you find strengths even in plays they don't have an impact.