When I bought my dvd recorder a few years ago, I copied most of my commercially bought videos on to dvd.
I found it time consuming as they record in real time and of course the quality is only as good as the original video.
Some would not record because they were macro encrypted - copyright - but you can buy a gadget that goes between the dvd recorder and the scart. This will work with some copyright videos but not all - different companies use different macros and so on.
Quite frankly, if your videos are available to buy in dvd format cheaply, I would consider buying new instead of making copies. If the video content is shown on television, you could of course record it from that.
The law is quite complex regarding copyright but if you make one copy of your video, and either keep the new recording with the original video there will not be a problem.
You must not sell or give away the new recording unless you include the original; nor sell or give away the original and keep the new recording.