You don't actually need the manifest files.
In Chrome, click on the menu, then More Tools, then Development tools. In the text box at the top, type 'm3u8'. Then load the game.
A bunch of files will show up, you're looking for the ones that start with 'chunklist'. Chunklist_ps is the audio, chunklist_b are the various video resolutions.
After the B is a number, which is the bandwidth allocated for that video stream. So the higher the number, the higher the resolution. 2628000 is the 720p file.
When you enter the code in the command prompt, it will pop up with stream details including the resolution, so you can double check there to make sure you have the right file.