On my Galaxy Tab S2 When I want to play an Mp4, I do not get the option to pick a video app "just once." It will go directly to the app and play the video. I will go settings and make that app NOT be the default, so the next time I click on the Mp4, I will get a choice of apps, but not the choice of "just once." So whatever app I pick becomes the default and the only way to get the app choice is to go into settings and un-default the app. I need the choice very time as I present product videos for work and different video apps truncate and stretch videos in different ways. On my Galaxy s8 phone, I always get the "just once" and always choose it. Maybe the Tab just doesn't offer the choice, but if it does, I'd like the option. Thanks!!