I agree, they did hype it up a bit more than they should have. But they feel compelled to do so given the nature of the production (low budget indie). Sales of DVDs pay back some of the overhead. I do wonder if any of the original Star Trek cast members get some compensation, even if under the table (I think being part of AFTA or SAG means you must get paid by guild/association rates, unless it's a volunteer thing).
Union actors get paid for the work they do on these films. The union would most likely not allow them to be in the films otherwise. The rate of pay would be on the low end, as these are non-profit 'indie' films. As for selling DVDs, that isn't really allowed at all. To my knowledge, you can give them away for free, but you can't sell them.