Double check your:
System specifications, especially RAM requirements, free hard drive space, etc.;
Updated OS and application software;
Driver and/of firmware updates for hardware;
Disk fragmentation and less-than optimal conditions for burning (too many background apps running, Anti-Virus disabled, etc.);
Your physical media is the right “flavor”- DVD-R is the optimal format for video-DVD. Sometimes even switching outvthe brand of media will correct burn issues.
If all else fails, utilities to diagnose failing or otherwise problematic hardware (on this case the burner) may be in order, bit only as a last resort.