They have way more right than wrong obviously. Reynad was the worst predictor and he only predicted 10 cards wrong out of like 130. That's better than 90% accuracy.I've heard several of the streamers mention they have issues with these type of videos because they cherry pick all the bad predictions and those are the ones that get the most attention. Could be interesting to do "What the pros got right" video to counter that sentiment, but I think the video is all in good fun either way.
Though a lot of the cards are pretty straightforward bad or good.
Then again if you take issue with these types of videos then you shouldn't be making prediction videos to begin with.