I have found that Discovery Education is the most useful. There is an abundance of great videos that you can use. Also, you can search for full videos or segments. Magic School Bus and Life videos are two of the many great types of videos available to stream in your class. Youtube brings up a lot of homemade videos, so it is not as easy to search for appropriate videos to use in the classroom. One great feature is you can easily create a video with your class and upload it to Youtube. We utilized this last year while our ducklings were hatching. Students were able to relive the experience from home and show their parents on our class blog.
This video shows great pictures of stages of the life cycles of a variety of animals.
This is a great video explaining "What is a bird?" found on Discovery Education. I cannot embed this video without downloading it so it is hot linked.
Copyright and fair use allows teachers and students to use images, videos, etc. if they are using a secure location (not for all of the public to view) for the content. This is new to me and great to know.
I downloaded Dropbox and found that it is a great program to hold all your files, pictures and videos. Now my files (pictures, lesson plans, etc) on my home computer and work computer can be in one place. I no longer have to email them to myself! :) You can log on to dropbox from another computer and you can share pictures, videos and files with other people.