We are sorry for your difficulties. Please let us know if it is happening with all video projects or a particular one. Is it a long video to download? What is the format type of the video? For now, the best workaround is to split the video timeline across multiple pages, download them individually, and then merge them using quick actions.
Besides it's always good to test the following: Reset the page by hitting F5
Clear your browser cache
Change your browser and use one of the following: Edge, Safari, Firefox, and Chrome (and only those 4). Please let us know if this helps.