It seems more and more that you can find someone to make YouTube an even more valuable tool then it already is in the classroom. There are several websites out there that allows you to manipulate the videos to your liking for your classroom. I had a student today tell me that they didn't use a YouTube video in a presentation because it was too long. At that moment, I didn't even think to mention the software out there that allows you to clip a section of a video to meet your needs. Below are resources to use in relation to YouTube.
1.) 100 Incredibly Useful YouTube Channels for Teachers - Another one of those list from another one of those Online College websites. Very useful though and separated into categories and subjects. Worth taking a look at.
CaptionTube allows you to create captions for your YouTube videos. It is free and easy to use and creates a different dynamic for the videos that you upload. It provides a transcript for your viewers.
Clip Converter is a site that allows you to take a URL from a YouTube video (and several other sites) and convert it to several different video formats that you can choose from. I do want to warn you though that on the main site it does mention converting Porn videos from specific porn sites, so use independently from your students and do not share it with them. The site can be useful if YouTube is blocked at your school and you have a video that you want to share from the site.
4.) YouTubeTime.com is a site that allows you to copy and paste a YouTube URL and then enter in the time that you would like the video to start (unfortunately it does not have an end time) and it will then provide you with a secondary link that will take you to a site to play at the moment in time you requested. I suggest that you read the bottom of the page to realize that you can do this anyway just by adding to the original YouTube URL.
Meep is an add-on for Internet Explorer that allows you to save and download videos straight from YouTube. Could be useful...if you are an Internet Explorer user.