Game Boy Advance Capture
From SDA Knowledge Base
If you want to speedrun a Game Boy Advance game, you are REQUIRED to use a Game Boy Player to capture the A/V footage.
The Game Boy player is an add-on to the Nintendo Game Cube that enabled the GameCube to play both Game Boy and Game Boy Advance games. The add-on contained a slot to load Game Boy / Advance games and a disc to boot up the player. While the Game Boy player still doesn't play games at a speed identical to the original Game Boy Advance, it is pretty close.
The Game Boy Player contains some picture filter and border options that you must configure when recording a speedrun. Make sure that the screen filter is set to "Sharp", the frame is set to #20, and that the screen size is set to "Normal." After you have that set up, just record as you would record a normal GameCube game. For reference, the GameCube video signal is 480i. This signal should be compatible with standard definition capture devices and some high definition capture devices.
As a side note, if you aren't a fan of playing Game Boy Advance Games using the GameCube controller, the website Retro USB sells some controller adapters that will let you use an NES or SNES controller instead.