Sometimes YouTube video won\'t play, or stops playing, or plays the video but no audio. I suggest the following steps:1) Use CTRL+F5 (CMD+F5 on mac) to refresh the page and try and play again\n\nIf that does not work then:\n\n1) Shut down the browser\n2) Shut down and reboot the computer\n3) Try again\n\nIf you use the greasemonkey scripts you can download the MP4 files and play them on the computer itself, instead of through the flash player. Install these and then you will see a \"download as MP4\" blue link at the bottom of the gray video information box. Right-click and save as a filename that includes the .mp4 file extension, and once it is downloaded to the desktop, just open into any installed video player.\n\nGreasemonkey (Firefox Addon)\n* https://addons.mozilla.org/en-US/firefox/addon/748\n\nYouTube High Quality (userscripts)\n* http://userscripts.org/scripts/show/23702\n\nDownload YouTube Videos as MP4 (userscripts)\n* http://userscripts.org/scripts/show/25105 download, firefox, plugin, scripts, troubleshooting, tutorial, youtube