I just downloaded it and Gspot seems like a very nice program. Unfortunatly it does not help in this case either, I have tried the other avi tag editors as well. When I try to add the RIFF tag info, the program reports that there is no space for it. The other AVI tag editors give similar type of errors. So I'm assuming the only way is if Gabest can implement this into Submux or change the way Submux works so that the tags can be changed.