Learn the keyboard shortcuts
The problem with YouTube's keyboard shortcuts is that they only work after you've clicked on the video player itself. Still, the numerous keyboard shortcuts are still useful; at the very least they limit the amount of mouse pointing you'll have to do. Check out a comprehensive list of YouTube keyboard shortcuts here. For quick reference: Spacebar plays or pauses the video, left/right is rewind or forward, and F activates full screen mode, and Escape disables it. Up/down controls the volume, M toggles mute, and 0 to 9 quickly skips to every tenth of the video.
Turn of automatic quality adjustment
Switch the YouTube player to full-screen, and the online video site auomatically tries loading a higher-quality version of the movie if it's available. A useful feature that's unfortunately not workable on computers with slow internet connections. Simply turn off this automatic adjustment by clicking on the gear button on the bottom of the player, and making sure "Never play high quality video" is checked.
YouTube Leanback: Perfect for Home Theater PCs
Want to watch YouTube videos from across the room? If you've got a large enough display—or have connected your PC to a large HDTV—just go to youtube.com/leanback. You'll end up on a stripped-down yet very functional version of the video site, allowing complete control through the keyboard. Leanback takes up the entire window, so there's no need to switch to full screen.
YouTube Repeat: Keep your favorite music playing in the background
It's no secret that millions visit YouTube everyday to listen to their favorite artists, which is why a repeat button has been a long-requested feature. But since the people behind the online video site have yet to implement it, if there are plans at all to do so, you'll just have to visit youtuberepeat.com to keep your favorites playing over and over again.
YouTube Disco: for music lovers
Speaking of music, you can quickly access music videos by visiting youtube.com/disco. Simply type in the artist or song you're looking for, and YouTube will generate a playlist that theoretically should appeal to your musical taste. Quick links provide access to a "Top 100" playlist, and the discography of top viewed artists.
YouTube Doubler: great for giving a scene some background music
Have you ever realized that two videos go well together, and wanted to watch them side-by-side, or at least view one video while listening to the music of the other? YouTube Doubler not only makes the dream a possibility, it allows one or both videos to be delayed, for syncing purposes. Feel free to play around with this rough example: youtubedoubler.com/4b6P. The only (and perhaps obvious) problem? The online service requires a fast connection to work properly.
Keep the encoding do's and don'ts in mind
YouTube supports a wide variety of video formats, but it's still worth paying attention when compiling the final video you want to upload to the site. Take the time to read through the service's own tips on encoding videos, to ensure the quality of your uploads. At the very least, it will save the trouble of deleting a stuttering video from your account, rerendering the source video, and waiting for the new upload to complete.
How to download and convert YouTube videos quickly and easily
It's amazing how YouTube keeps years of video at your fingertips at all times, but what if you wanted to save a specific video for posterity? There are numerous applications, especially for Windows PCs, that automate downloading YouTube videos and converting them into a format watchable on your computer. Our personal favorite: Freemake Video Converter.
Check the speed of your connection
If YouTube videos aren't loading properly on your end, you can check out http://youtube.com/my_speed for statistics on how the well the video site operates with your internet connection. Find out how your YouTube experience compares to not only other people using your ISP, but to other people within your country, and YouTube's global average of 5.98 Mbps (as of this writing).
Using YouTube advanced search operators
Google owns YouTube, so it makes sense that some of the things you can do with the search engine work on the video site as well. Put quotes around the search term (example: "Tom's Guide") to search only for exact matches. Put a plus sign before a word ("+Guide") to ensure all search results will include it, and a minus sign ("-Guide") to ignore any results with the word. Lastly, use "intitle:" ("intitle:Guide") to include results that have the word in the video title.