While we lost the planned sequels to 2006's Maverick Hunter X for the Sony PlayStation Portable, we'll always have the original game (and it plays great on the PS Vita, too).  In addition to the remixed soundtrack and new playable character, the game also includes a special animated prequel mini-movie entitled The Day of Sigma that chronicles the adventures of Mega Man X, Zero, and Sigma prior to the events of the adventure.  Originally you'd need to unlock the video in-game to watch it, but it wasn't long before people recorded it and set it loose on YouTube.  Unfortunately, those recordings always topped out at standard definition resolution at best.  Now, however, we have a true high definition 720p version of the movie on YouTube for your enjoyment.  Here's Rockman Corner with the information on how this HD version came to be:

Unlike previous rips (which tend to be oversaturated or washed out) Silk Encoder actually went into Maverick Hunter X's source files, ripped the video and audio, synced it, and encoded the whole package to 1280x720 in meGUI. It's a big step-up from the 480x272 source and it should hold us over until Capcom provides an official HD release. If they ever do.

It's a shame that the Maverick Hunter X sequels died on the vine; can you imagine seeing some of the classic later events of the Mega Man X series depicted in short films such as this one?  While the X series eventually sputtered to a stop in the PlayStation 2 era, the first four games in the series are beloved and would have provided plenty of source material for more movies and game sequels.  It's such a lost opportunity.