To answer the question: How to downland and save videos in the systems?
Please check out the following techdocs. You can have Service Desk Tomcat to have Save As for video attachment when user click on the attached video files in Service Desk tickets. It would allow users to save/download the video to the local system instead of using the browser to open it. Then, open/play/view the downloaded video as long as your system have proper video player to view the type (wmv, mp3, mp4, avi, mpeg) of video.
TEC1212791 - pdf Attachments with Microsoft Edge
https://support.ca.com/us/knowledge-base-articles.TEC1212791.html
You can add the video format (mp4) to the save_as_dialog_ext like the techdoc for pdf type attachment.