With the creator's permission it's fine, but I don't know what benefits being on a community channel would offer besides exposure. If you put a video on your channel and the same exact video on a community channel, even if you put a link the the original video in the description, the community channel is taking away views from you. If you produce an entirely new video for a community channel, you'll get exposure sure, but that's about it. The community channel is benefiting more in the long run because they're continually getting revenue on these smaller channels who are banking on people liking the video enough that they'll check out their channel. It's a gamble for the smaller channels, but then again they aren't losing too much from it. The community channels lose nothing and gain everything.