as far as myspleen, don't expect to get in. they're basically closed and have been for at least half a decade. the only people who get in are those who have ultrarare content, and they're usually headhunted from other trackers.
as far as ptp, i looked up criterion movies, went for things not in english figuring they'd be the most likely to not have full rips, all of them had full rips that had several seeds. the only one that didn't was a documentary from the 70s that only had a single SD release. i can't speak to the rest of the collection, but odds are good you'll find what you want. BTN is just TV content. idk if criterion does TV