With TwitterXDownloader, you can save any Twitter/X video to your iPhone or iPad in just a few taps — no external apps required.
Open the Twitter app, tap the Share icon on the tweet with the video, then select "Copy Link".
Open Safari, go to TwitterXDownloader.com, paste the link into the input box.
After processing, choose HD or SD quality and the download will begin.
Tap the Download icon in Safari, then select "Save to Photos" to keep the video in your gallery.