The quality of the skits and ''Weekend Updates'' has zig-zagged over its 31 seasons but when it comes to spoofing TV commercials, Saturday Night Live has been a model of consistency: usually inventive, frequently audacious, almost always genuinely funny. Saturday Night Live: The Best of Commercial Parodies has collected most of the best of those mock ads, and though it feels a bit weighted in favor of the last five-to-ten years, it does offer up golden oldies from every era: Dan Aykroyd delivers his classic ''Super Bass-o-matic'' sales pitch (''Fast and easy and ready to pour!''). Eddie Murphy, as the Little Rascals' Buckwheat, shills for the album ''Buh-weet Sings'' (''Unce, tice, fee times a mady...''). Mike Myers, Dana Carvey, and Jan Hooks demonstrates the bounciness of ''Happy Fun Ball'' while announcer Phil Hartman cautions to discontinue use ''in the event of itching, vertigo, slurred speech, temporary blindness...'' And current cast members such as Amy Poehler and Maya Rudolph get a big showcase as they hawk ultra-girly products from ''Mom Jeans (cut generously)'' to ''Woomba: From the makers of Roomba...the first fully automated, completely robotic feminine hygiene product!''
Former Poehler-Rudolph costar Will Ferrell also gets a lot of face time here. In addition to appearing in more than his share of faux ads, he also serves as the disc's host, leading us on a tour of a fictitious Madison Avenue ad agency. This prolonged sketch repeatedly interrupts the flow of vintage SNL commercials, but doesn't really go anywhere, except to a casting office, where Ferrell attempts to audition for, yes, another feminine hygiene product. Get it? He's a guy! But he's not a very funny one in this waste of several minutes that could have been devoted to more vintage SNL commercials like, say, the old Chevy Chase/Dan Aykroyd/Gilda Radner ''Shimmer Floor Wax/Dessert Topping'' gem, that is curiously missing from this collection. It didn't even make it into the so-called ''Extras'' menu, which consists of 10 additional spoofs, only two of which deserve to be on a ''Best Of'' collection. But those two Ferrell's ''Colonel Belmont's Old-Fashioned Horse Glue'' ''our promise of quality: Pure, mutilated horse paste!'') and the Michael McKean/Janeane Garofalo/Chris Elliot ''Eterna Rest'' casket mattress ad (''We keep working even though you're dead'') almost make up for the other only okay choices. They rightfully belong to a tradition, that after, three decades, ought to be good for at least a Volume Two.