Pros
Yes, I would do it, absolutely, but I would want a walking narration from the pro so you could pick up the subtle nuances of the game. For example, 'I am shooting the 5 ball with low right english so I can place my cueball in this area for the 6. It is important because I have to get up corner shape on the 7'.
Just watching someone doesn't guarantee that you will learn something. B and C players would probably be more likely to learn something, than an A or A+ player. It is a lot easier for a B and C player to up their game a level, much more so than an A or A+ player.
A and A+ players would do it to see where they stand in the foodchain.
B and C players would do it to learn something that will advance them to the next level.