You're welcome

...And yeah, that is another possible workaround. Here are anyway, just in case they can be useful, two freeware (unless something had changed, but I don't think so) lossless avi codecs supporting
Alpha channel for compositing:
I remember to have tested the first one (Huffyuv) long time ago and it worked quite well to me (although maybe it could require some new testing), about the second one, I think I never tested it but I heard good things about it so I've decided to included it. Of course, both generates HUGE files as they are lossless.
EDIT: Hmmm, after some quick tests, the first one still seems to work quite well, but I'm finding the second one (Lagarith) a little buggy; well they are freeware but better choices could exist nowadays out there tho... Anyway, I think I'd simply do what funksmaname said, but whatever workaround which with one feels more comfortable (obtaining similar results) can be the appropriate.
Well, greetings!
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