Someone was working on a mod that made just about all major UBB images Flash-capable... I don't remember whether that got off the ground or not, though.
Unless this is what you've already done, you'll probably have to go in via the files and hard-code the flash into it. The buttons *should* be in ubb_lib_posting.cgi, though I can't be certain. Look for $reply_wording or something similar (mebbe you'll have to take out the underscore or something). Sorry I can't be more specific, but I don't have a set of files sitting in front of me at the moment.
---Skorpion
