I should clarify: I don't think they're adding backdoors maliciously. It's their conduct -- proceeding despite the concerns raised, attacking critics, etc. -- that is greedy and malicious.
Considering that their Kickstarter was shut down 6 months ago due to their lies, and that they started up again at Indiegogo despite the warnings, and that they've been concealing information and attacking their critics through sockpuppets? Yes, I think it's fair at this point to call them malicious.
Once I had both versions of the files, I looked at them in a hex editor. Since there were some null bytes at the beginning of the video file, it wasn't hard to guess the string they were using. I'm not going to post the file themselves (for obvious reasons), but here's the first 16 bytes of the unencrypted and encrypted files (in hex and ascii, from xxd). Unencrypted:
You're right, actually. I'm glad it's broken, because it's a lot easier for me to watch the videos I purchased without the DRM. I was just struck by the audacity of their marketing claims.
My modifications are on lines 553-556. The compiled app "fixes" the .mov file just long enough for it to be loaded into the player. If you have Leaping Brain's player installed (often branded with the content owner's name), the .mov files are in a hidden .media folder. On my Mac, they were in $HOME/Library/Application Support/LeapingBrain/catalog/$VIDEONAME/.media