There are many ways to capture video to use in a project with Photoshop. Many computers have a web cam that can be used with programs like Quicktime or Photobooth. Videos from a smart phone can be captured with programs like iPhoto or using apps like Dropbox or email.
To capture video in Quicktime, open Quicktime, go to File > New Movie Recording. You will need to make sure to save the movie file when you are done recording. This will create a 1280 x 720 (720p) video with AAC (similar to mp3) quality audio.
When capturing video in Photo Booth the file will have the same quality as Quicktime, but it is stored in a hidden folder associated with Photo Booth. The easiest way to edit it in Photoshop is by dragging the thumbnail from Photo Booth to Photoshop.
When capturing a video with a Smartphone, depending on the size of the video you may want to use different programs. For anything lower than 10mb, it may be easiest to use an email application. For larger files, something like Dropbox or Google Drive would be useful. Depending on your device you may have different video and audio dimensions and compression settings.
In class today try to capture video using whatever device you have available or one of the computers. Everyone should try taking some video, importing it into Photoshop and combining it with other moving images or sound elements.