It's hard to tell whether they use AI for script generation. After having seen enough of those recaps, the humor seems to be rather mechanical and basic humor is relatively easy to get from an LLM if prompted correctly. The video titles also seem as if they were generated.
That said, this channel has been producing videos well before ChatGPT3.5/4 so at the very least they probably started with human written scripts.
I thought it was just text to speech when I happen to saw some of those videos. And it seems to have been consistently similar since before ChatGPT etc. Why do you think titles are AI generated?
I feel like it might actually be quite complex for AI to pull up the perfect clips and edit them with the script, including timing and everything. Maybe it could be made automatic, but nonetheless it would be a complex process and I don't think possible few years ago. I know Gemini and possibly some others can analyze video if fed to them, but I'm still skeptical that this channel in particular would have done it, when they have always had this frequency of uploads and similar tone.
Also I think there's far better TTS now with ElevenLabs and others so it could be made much more human like.
That said, this channel has been producing videos well before ChatGPT3.5/4 so at the very least they probably started with human written scripts.