I'm with you. Slows the game down way too much.
The benefit (correcting mistakes) just does not outweigh the cost (slow game...disrupting everyone's rhythm). The way this is executed exacerbates both sides of that equation and I'm pretty convinced you won't see many 'reversals' (see rationale below)
First...correcting mistakes. There will be very few reversals (even if warranted sometimes) because: 1) I assume there are not multiple "good" angles caught by the limited camera's; 2) You are relying on "college baseball budget" technical crews to actually have the camera properly aimed at the play; and 3) The umpires "reviewing" the video are the same individuals who just made the call on the field. Human nature would be/is to not admit a mistake...anything that can be rationalized as "not indisputable evidence on video" will stand as called.
Second...slowing game down. The process seems to be... 1) Coach requesting review comes out of dugout & approaches home plate ump to "discuss" the situation; 2) Ump then calls a pow-wow with the rest of the crew to "talk" about something and take notes on a piece of paper; 3) 2 umpires retire to somewhere out of view via the dugout; 4) Eventually, emerge to make the call. The 3-4 reviews I've seen so far probably (I didn't keep a clock) averaged 4-5 minutes to complete.