Or did the movies all come on DVDs?
The laptop is about 4 years old and came with W10 installed, which was
changed to W8.1, for G3-dongle compatibility.

It's got a HDMI socket, which the TV also has.
So would the video show on the TV? And what about sound?
What preliminary tests can I do with my mate's selection of "CD movies"?

TIA.