they just never take it off

[Torchwatch]

The gay porn industry sell oral and anal penetration, in a speedo sex scene there may be bulges, touching, licking, sucking, pre-cum and cum but without penetration it would fall outside the usual market.

Getting hold of a video camera is easy these days, many people already have them (if not of great quality).

Finding performers willing to take part in a speedo sex video is harder, do you want hot young twinks or real guys of all ages and conditions? The twinks will want paying though the others might do it for fun.

The hardest part of making an interesting porn movie is finding the locations, a speedo movie should take place on a beach, by a lake, or around a pool. Sex outdoors is fun, but having someone filming it invites attention. Only the rich have their own pools, and they rarely want gay sex in their gardens. There are places you can hire but a low budget amateur movie would not be able to afford the price.
You could always show the performers meeting on the beach and then jump to the bedroom or lounge.

The actors would need to wear unlined suits in light colours for the bulges pre-cum and cum to show. If they are shown swimming then they would have to put on dry suits for the sex scene to show damp patches.

It would not be impossible to do but would take some planning, and speedo inspired performers.