The vidtut_barrel.zip file you have requested: Tutorials and Guides / Texturing / Photoshop CS Barrel Skinning Tutorial - 23.61mb is not available. Perhaps try browsing all files for the game Half-Life 2 and upload any files you want to share or are missing. This is the only information we could locate:
Install the codec "tscc.exe" before playing and then run the video. There is no audio, but its straight forward enough to follow. When dodgeing and selection the "shift" key is used to dodge straight lines and to add more to a current selection. Other than that, everything is on the screen. Enjoy!