I opened eac3to to demux an mkv file, at the end I noticed warnings like the following:

[v01] Video has a gap of 1 frames at playtime 0:26:08. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:26:10. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:26:13. <WARNING>
[v01] Video has a gap of 2 frames at playtime 0:26:15. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:26:22. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:26:25. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:26:28. <WARNING>
[v01] Video has a gap of 14 frames at playtime 0:26:30. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:27:12. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:27:15. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:27:18. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:27:21. <WARNING>
[v01] Video has a gap of 1 frames at playtime 0:27:24. <WARNING>

And more…

What does this mean? What's wrong with the video?