Identify what you have
A DVD-Video disc opens in Digitize Discs. A disc holding loose video files is a data disc: use Convert Video. For tapes, arrange a separate capture service or suitable capture hardware first.
Choose a modest first project
Start with one readable disc. Check the main movie and chapters, preview the content and save an MP4 or MKV file. Do not discard the original.
Name and verify your recordings
Use names that identify the event and approximate date. Play sections from the beginning, middle and end, then copy the result to a second drive kept separately.