Got that shiny new rMBP and want to play some stunning videos. Or is youtube now slow for you in Safari? This is a solution. EDIT 1: Some of you are replying that this has suddenly stopped working. Try reinstalling the plugin and flash. It may help. Post AND quote me if you need help. EDIT 2: It seems that clicktoflash will randomly stop working after an extended period of time. No idea why. The only fix I know of is the reinstall and reconfigure it. EDIT 3: Posted a video at the end showing how it should look. Video is not embedded. For this guide I will be using the timescapes 4k rapture trailer. You will need a mac running OS X Lion or Mountain Lion. This is how Timescapes looks with flash player installed. Nothing unusual but playback at very high resolutions is takes up a lot of CPU and battery. Now this is the same video with HTML5. Same UI for the player. At high resolutions the video is just unplayable. Heck at low resolutions it is unplayable. Now the fix. 1) Go to the HTML5 youtube trial page here, and make sure you are not in the trial. It should look like this. 2) Download ClickToPlugin and install it. Clicking the link should auto download the file. 3) Go to the "Media Player" page for preferences. Mine looks like this. I don't have an ATV but if I did I could stream videos to it. (Kinda useless with airplay mirroring in ML.) In the "Shortcuts menu" page enable downloads. My page looks like this. Now lets go back to that timescapes video. This is what it should look like now. Looks familiar? Its quicktime X. Hovering over the left side will let you choose your resolution if you want to play in anything other then what you set as a default. Right clicking on the video will also give you the option to download it in whatever format/resolution you are currently playing it in. You can even open it in quicktime X. This is how it should look. (Video) Enjoy.