How to get a screenshot of what’s on the AppleTV

I'm not sure if this will work in your case, but someone on this forum seems to have had some success in a similar situation by simply changing the file extention from .mp4 to .m4v.

They were also using handbrake.

What I would do is:

• Have only 1 library
• Make sure that iTunes is configured to keep all your media organized (and point your single iTunes Library to your preferred disk)
• When adding files to your iTunes library hold down Option/Alt to let iTunes know that it shouldn't copy the file to where your library is

This way all your data will be organized by iTunes except for the large files that should belong on your largest external disk in the first place.

Cheers...