Jing is a free application that lets you capture basic video, animation, and still images, and share them on the web. There are lots of other similar software systems out there, including much more robust and expensive ones, but Jing is very simple to use, it's free, and it's available for both Mac and Windows operating systems. Now that you're working on the web, it's fairly likely that you'll need to capture screenshots, and capturing video while you navigate through a website could be a really effective means of providing feedback on your classmates' sites.
Jing is not a browser-based application, so you'll need to install it onto your computer. Go to the Jing site and, if you'd like, watch their one-minute introductory video, and then just click on the big Free Download button at the top of the page.
Once it's installed, it will automatically open a brief tutorial activity, which you might find helpful. Notice that the tutorial walks you through sharing images via Screencast, another service by TechSmith and at the end of the tutorial, it directs you to create an account. Go ahead and do so, and click on the link in the confirmation email that they send to you.
The second step is to configure that Screencast service. If you didn't create an account from the tutorial already, then just go to the site and sign up for a free account.
Jing will let you download videos or images to your desktop, which is great. However, it can only export videos in .swf format, which is not very helpful because those files are difficult to share. It is possible to convert .swf into .mp4 video files and then share them directly, but thankfully the Screencast service is designed with a number of layers of privacy and security in order to allow you to share videos without too much concern. Screencast has a helpful video overview on how to organize content and set privacy levels.
If you are using Jing to record screencasts for feedback on your peers' work, it is probably going to be important that you set appropriate levels of privacy.
Jing has a helpful tutorial video showing you how to take your first capture.