HOW DO WE PLAY A FILM THAT WE HAD TO DOWNLOAD ON A CD ON A DVD PLAYER?

Most set-top dvd players can play vcd's. I presume that's what you want to do with the video. You have a choice of vcd or svcd. SVCD is better quality but you can only fit less on a svcd. Perhaps only 40-45 mins. Whereas a vcd can hold 60-70 mins or more if you overburn but that's not always advisable as it can damage your burner if it doesn't support it.

Nero & Roxio are the 2 best common burner programs to burn vcd's. Select video format to burn, select vcd as output, & drag & drop your video file into the interface of the burner program or select it from the open menu. One important thing you should remember is that vcd's should be burnt at the minimum possible speed!!! If burnt at high speed, often the set-top dvd player won't be able to read it.

If a dvd is what you'd prefer to burn it onto then same principle but instead you choose dvd as the output. But to burn a dvd your burner hardware needs to be a dvd burner & your software also needs to support burning dvd's.