The video cache location cannot be changed
The default location is set as :
Windows : C:/Users/userName/AppData/Local/Adobe/Lightroom/Caches/Video
Mac : Macintosh HD / Users / [your username] / Library / Caches /Adobe/Lightroom/Video
The video cache is generally generated when Lightroom tries to read the video files at the time of import or processing.
Lightroom maintains a video cache to help with the performance of viewing and manipulating video files.
Ok, but you should really allow us to change this location.
For everyone who struggles with this bug, you can use this as a workaround:
Just change the directory from the Downloads folder to:
"C:\Users\YOURUSERNAME\AppData\Local\Adobe\Lightroom\Caches\Video\Media Cache Files\"
Also, change the timeframe in the .bat file from -30 to -0, that will delete all the files in the folder, not just the files older than 30 days.