@user8bAs7iYzAe Here is our page on the Samsung Cloud that will fill you in on everything about it, including syncing to other devices. https://www.samsung.com/us/explore/samsung-cloud/#back-up,-sync,-restore
It depends on where they are being saved and where you want to move them to. Are they saved in Samsung Cloud drive or are they in a gallery synced album for example. There are several different methods that can be used with synced albums that give you different results for the synced video file.
The basic way to move a file in Samsung gallery is to open the album that contains the video file that you want to move and long press on it to select it. Tap the 3 vertical dots at the top right corner and select move to and then select the album you want to move it into. You can also use my files internal storage /DCIM /and find the gallery folder that contains the video file. Long press to select it and choose move from the panel at the bottom. Once you have done that use the back button to go back into internal storage and open the folder you want to move it to and Tap move here at the bottom of the page.
My Files also works well if the video file is saved in Samsung Cloud drive.
Open My Files settings and select edit my files home. Turn on Google drive. Go back to the my files home page and you should see Google drive listed. Select it and sign in using your Google account ID and password. Go back into internal storage find the video file. Long press to select it and then select move on the bottom panel. Use the back button or gesture to go back to the my files home page and select Google Drive. Open the folder you want to move the video file into and select move here on the bottom panel.
When you're in my files settings you can select any of Cloud accounts and log in or out. Also if you have more than one account with Google you can switch accounts.