Really confused

So I was really excited to use this app bc usually the other screen recorder apps cost money :/ so when I saw this app I thought it was gonna be a good app but I was testing just incase so I took a 5 min video so when I clicked the record button I got out of the app but I didnt close it I just made another tab and played a game.But when I was done I went and erased the game tab I was playing on for my video and when I went back to this app I clicked done recording and I went to files and Clicked on the video and it was just frozen and only recording this app Im REALLY confused plz help

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