Videos that don't have thumbnails stutter while I play/move forward/move backward in VLC

Question

I download tutorial videos and study them at my convenience.

I noticed there are two types of videos in my case:

1. Those that have a thumbnail preview after I have downloaded them.
2. Those that just show a VLC icon.

In the second case, when I press the right/left arrow key to move 10 seconds ahead or behind, the video takes a second or two to load, which was not the case with Type 1 videos. Both videos are MP4.

This video below stutters

This video below is the smooth video

Can somebody tell me how do it fix it ?

System Information:

Windows 10 home, Intel core i5 7200U @2.5 GHz, 16 GB ram, Intel HD graphics 620

VLC version: 3.0.11 Vetinari