4K stock videos are available in the PosterMyWall editor. Click 'Media' on the left bar in the editor, and select 'Videos'.
In the stock video tab, select '4K' as the video size.
Only 4K videos will be displayed now. 4K videos are easy to spot as they are labeled as '4K' while getty images are labeled as 'g'.
Select a video and it will be added in the editor.
Learn more about 4K videos in this article.