It seems as though this particular DVD only has one audio track, and the only way to switch between the English and Japanese audio is the language option on the main menu of the disc. (Which I didn't notice earlier. Heh.) The PS3 must just read the tracks differently than VLC or WMP, enabling it to switch languages during playback without having to return to the main menu. Odd, seeing as VLC only detects one audio track and one subtitle track.
Anyways, problem solved! Thank you!
MSI B75MA-P45 Motherboard
Intel Core i3-2100 3.10GHz
8GB DDR3 1333MHz RAM
SAPPHIRE AMD Radeon HD 5770 Vapor-X
Samsung 840 EVO 120GB SSD (Windows 7 Ultimate)
Toshiba 2TB HDD