Video tape spools are pretty easy to remove from the cassette—take out 5 screws, pry the cassette apart, cut the tape (be sure to rewind the tape before removing the screws) and set it aside. Toss everything else into the box to ship to greendisk**.
Audio tape fiber just has to be snipped and used straight from the cassette since the cassettes don't really come apart and if they did you'd just have a mass of loose fiber rather than neatly spooled tape.
Video tape can be a bit squeaky when you're working with it; haven't noticed much sound coming from the audio tape. I would call that ironic, I think.
I only double up the video tape for sturdy, free-standing items like shopping bag bottoms or boxes and things. Audio tape is not really usable in a single strand. I've experimented with multiple strands—3, 5, 6—to get the results I want.
Video tape comes in a flattering black color—consistently, no matter who made the tape. Audio tape comes in a range of shades from black to light brown and varies by manufacturer.
*Before you ask, I'm good on my audio tape stock at the moment. I'll put out a call when I need more.
**I send pretty much everything except the tape along with bum CDs and other techno-trash to greendisk.com.