In addition to recording, VidGrid also allows you to upload videos from your computer. These can be videos you have created or captured in many different ways, anything from a quick selfie video on your iPhone to a short documentary you have created using equipment available at the Digital Media Lab.
There is a maximum file size of 5GB, which should be sufficient for all but the longest and highest quality video files.
Watch this short demonstration from VidGrid on how to upload a video, and remember that this functionality is available inside Canvas using the VidGrid button as well.