Wont let me save YouTube videos anymore.

I make edits with Anime clips I can find on YouTube and edits with Youtubers that I also find on YouTube, and now I cant save a single YouTube video. It always tells me that it cant download and that I have to pick another. This happens all the time, Ive tried to delete the app and re download it and its still the same.

Mihamih about VidLab・Video Editor & Overlay, v1.15