Try stopping and restarting the app, also try resetting Ad ID. Different things work on different days. Experiencing the same thing, but doing the above works. In most cases can finally get the 150, but have had it stop with only 146-148, and nothing seems to work to get the missing.
The other thing I have noticed, slow down just a hair on getting a new video. A number of times it seems to just search for a video, but if I wait just a bit it loads them again.