2/6 is... not correct, and I would appreciate more explanation of the problem. If the AVI decoder is supposed to always output PTS but GStreamer doesn't give them to us, I'd think the right thing to do would be to calculate the PTS ourself by adding the last sample's PTS and duration. [Or modify GStreamer?]
6/6 doesn't seem right either. According to the bug report it's for a deadlock; what's the deadlock?