eBay is a really good source- just search for "roatan" and be rightly amused- today it came up with 89 hits... some are the odd commercial items that have co-opted the name.... sunglasses and shoes. There, you will find DVD's, right now there are three for $6 that came out of Fantasy Island's label, likely they were made by Tim Blanton of Cocoview. Timmy's own label DVD's appear on eBay fairly regularly. (Then, there's the guy

who keeps putting up the same battered Roatan postmarked envelope over and over)
If you are trying to entice a group, remember that the underwater scenery and critters vary dramatically depending upon which area you are staying within. The two major, regularly travelled zones are North/West and South Shore. Very different below water, but since portions of any pro DVD are featuring above-water stuff, they are all entertaining.
If you are going through any sort of tour operator like Roatan Charter or similar North American booking agent, they will likely send you a
free DVD. Although it is a commercial, it's pretty much so what tourists are buying on their way out at the airport.
Have it for free, just ask the agent, or if you are dealing with a resort property direct- ask them for one.
Note to all SCUBA club entertainment directors: At local retail SCUBA Shows, ask for free DVD's at every display booth. If none are available, call, write or eMail your request- tell them what you are going to do, they may offer you a t-shirt or something even better for a raffle prize. If all else fails, run some Sea Hunt episodes and have a dorky quiz afterwards!