There are two commands in Linux that can be used in order to view memory usage. The first one is the top and the second one is free. There are a lot of people who may not realize the importance of having enough memory until they do not have enough space anymore in order to save the media file that they want.
You need to be aware of the available memory that you have. If you do not have enough, there is a big possibility that you need to delete a few items that you have saved before in order to make space for the new items that you will also save.