horizontal line on the movie when is plying

We don’t know which type of camera you have, so here’s the common causes for both:

Tape based ones are a multi issue mess, but are thankfully less common. What you need to do with those is start with a cleaning tap that works with your camera* and see if that works to clean the heads in the camcorder. If it doesn’t, you generally need to do it manually with isopropyl alcohol. If neither of those work, change the tape. The issue is finding a new one, since nobody makes new 8mm/Hi8 tapes, so you need to find a NOS pack somewhere like eBay.

*If you have a Hi8 camcorder and can’t find a 8mm tape, it should work. Using a Hi8 tape in a 8mm usually doesn’t.

If that doesn’t fix it, then your CCD is bad. Not worth fixing that issue on many of these, as most 8mm/Hi8 and MiniDV camcorders are easy to get used replacements for.

Digital based ones are usually the sensor as there is no tape hardware to check, but it can also be the memory card. If you have issues with 2 memory cards, then the issue likely lies with the sensor. Again, repair may total out the camera.