eBay's HTML & JavaScript policy (doesn't seem to exclude flash, but if your item is prohibited, it will automatically be stripped with an error message): http://pages.ebay.com.au/help/policies/listing-javascript.html

Some other info you may find useful (not all that well versed in this stuff, myself, but it's from 2013 and written by ShipScript, who are pretty knowledgeable, so should be relevant): http://www.ebay.com/gds/Auction-Template-Help-Add-Video-or-Sound-to-Auctions-/10000000000109259/g.ht...