For precise 1GB, download a larger file then trim with ffmpeg:

"Need a Large Video File for Testing? Look No Further!"

For testing high-capacity systems, you can source 1GB MP4 files from dedicated network testing sites or royalty-free stock platforms. If you need a file that is exactly 1GB, generating one via FFmpeg is the most reliable method for precise specifications. Direct Download Sources

If you're in need of sample MP4 video files for testing, I highly recommend checking out this resource. The 1GB file has been a game-changer for my testing workflows, and I appreciate the convenience and variety offered.

If you download the same file twice, your OS and browser will aggressively cache it. Use curl with --header "Cache-Control: no-cache" or test in private/incognito windows.