What is causing these glitches and what can I do about them?

[DaneClark]

I've been editing MP4s in coolcut and they keep coming out with occasional glitches like the one in the enclosed picture. I've been ripping DVDs with Wondershare and MakeMKV and I could be wrong but it seems like these glitches don't appear until the final MP4 made in coolcut. Seeking through videos made in MakeMKV will sometimes show glitches that never actually appear when I watch the playback in coolcut. Someone please help me figure out what to do about this because I had almost an entire day's worth of work ruined by these glitches.
[Attachment 86993 - Click to enlarge]
I should note that I am between jobs and can't afford any better editing or ripping software.

[LigH.de]

I guess you are cutting at any arbitrary frame in the video, not just at I frames at GOP (Group of Pictures) borders.

MakeMKV will just extract any video and audio on your DVD and repack it into an MKV container without re-encoding, so the MKV will contain MPEG2 video and probably AC3 audio in most cases. I don't know what Coolcut does, will it convert the MPEG2 video from the DVD in your MKV to another video format which is more usual in an MP4 container? (MPEG2 inside MP4 is not very usual, possibly rather MPEG4-AVC ~ H.264, I would assume.)

If your video gets re-encoded while saving the copy in an MP4 container format, it is recommendable that the cutting happens before the encoding, but only logically, so that the encoder gets a sequence of selected video ranges to encode, but the material is not really altered on disc, or there is a risk that your cuts cause video frames which are compressed in a way that they store differences to a previous but now cut off reference video frame.

Don't be afraid of costs. Good video editing software completely for free does exist, e.g. ShotCut.

[DaneClark]

I'm not very tech savy, I just need someone to explain like I'm 5 how to get these videos to not have those kinds of glitches when I edit them in Coolcut. I would prefer to keep using Coolcut because I've been turning down the saturation on everything by 25 in Coolcut so that they look nicer on my TV when I play them from a flash drive and I want everything to be consistent. So far these glitches only seem to occur on things that were ripped from commercial DVDs, things ripped from homemade DVD-Rs never have this issue. Although there was also one instance where these kinds of glitches appeared in footage that didn't come from a commercial DVD but there was footage from a commercial DVD elsewhere in the same video.

[DaneClark]

someone PLEASE. i just found one of these glitches on an mp4 made in coolcut that had absolutley no footage taken from commercial DVDs and had another day's worth of work ruined. I have high functioning autism and need someone to explain like i'm 5 how to make these glitches stop appearing in coolcut videos PLEASE This is making me VERY anxious