The downloaded videos are compressed to low quality

[jianzongwu]

Hello, I used the download script to download validation videos but found that they are compressed a lot and, as a result, of low quality. Do you have any idea about this? I guess this may be caused by YouTube compressing the videos when downloading.

The images above are extracted frames and there seem to be many pixel patches, especially on the background

Does anyone have the same issue as I do?