This is a good question. What model of Canon Rebel camera do you have? There may be a few things going on with your camera turning off by itself.
First, check your battery strength. If your battery isn't charged sufficiently, your camera will shut down automatically. More than likely though, your Auto Power Off setting in the menu area is set to one minute. This will cause the camera to turn off by itself after that time.
When you're shooting video and after the camera turns off, can you press the shutter button half way down to have the camera turn back on? If so, it sounds like the Auto Power Off feature may be the culprit. To check this out, press the Menu button on the back of the camera. On my T7i, this feature is under the yellow wrench menu area and it's the second tab in. Depending on your model, things may be slightly different. Use the dial on the top of the camera to scroll between menus until you see this feature. When you do, use the up and down arrow buttons on the back of the camera to highlight it and then press the Set button to select it. Once inside this feature area, choose the Off option and then press the Set button again. This will turn the feature off so your camera won't turn off automatically anymore. To exit the menu area, press the Menu button a few times until you're out.
Please let me know if this works or if we need to investigate further. Thanks!