Game trailers for the games will be great. I know old gamers know these games but with trailers we can show these great and old games to new gamers too and for me trailers are better than motionless screens. What are you saying about this?

Quite a good idea, but it will cause higher GOG servers load.
But if it's don as a feature for registered GOG users it can make more people register and eventually buy games.

Maybe linking to existing videos like youtube etc. and monitoring traffic could be usful and less taxing on the GOG servers.
Alot of the really good older games still have maintained fan sites too so it might be an idea to point people to those treasure troves aswell.