I have recently stumbled across Youtube channel of KengaJr24. He’s got a number of concert recordings that I’m not too concerned with. But if you wade through those, you’ll find several videos of top Major League pitchers throwing their warmup bullpens before starts at Fenway Park.
What’s cool about his videos is that he tapes from directly behind the pitcher warming up. You get a great view of their stuff that you won’t find very often.
He has some other pitchers posted, including David Price and CC Sabathia. Check out his channel and watch them all, you won’t be disappointed.