Jumpy progress bar and corrupted downloaded video

The progress bar jumps randomly like it's almost 80% with 40 seconds remaining and suddenly it's 20% with 6 minutes and then jumps again to random progress.

Even when it finished downloading (at least that's what it seems), the video either gets corrupted and unplayable/unable to be rendered by any video player OR it is partially corrupted in which it will be playable up to a certain portion of the video.