There could be a few reasons why the "Save As" video option is not on your iPhone. One possible reason is that the video app you are using does not support the "Save As" feature. Not all video apps on the iPhone offer the option to save videos with different filenames. Another possible reason is that your iPhone is running an older version of iOS that does not support the "Save As" video function. In this case, you can check for any software updates and download the latest version of iOS to see if it resolves the issue. Additionally, if you are trying to save a video from an external source, such as an email or social media platform, the app may not have the permission to save videos to your device's storage. Make sure you grant the app permission to access your storage in the settings.