GLSEN/Gay, Lesbian and Straight Education Network, Judy Shepard
Several aggressive toughs walk toward the camera shouting epithets including, "faggot," "queer," "homo," and "What are you, a fag?"
It then cuts to the mother of slain Wyoming student Matthew Shepard, who says, "The next time you use words like these, think about what they really mean." (Shepard died October 12, 1998, of wounds from a gay bashing after a short coma.)
Pictures of Matthew are then shown, with the words "Murdered because he was gay." And then "End hate."
The spot ends with his mother Judy crying with a whisper, "There better not be a next time."
This ad, though created in 1999, got wider viewing in 2001 when MTV and the Grammy Awards came under fire for aggrandizing homophobic rap artist Eminem. The networks aired the commercial as an offer of balance to gay activists.
Of course these reasons are irrational and immature, but this applies only to certain youth.
Youth today are more accepting of LGBT people than previous generations, due to awareness and exposure(People in their lives are are coming out) and recognition by legal system (Lawrence vs. Texas, etc).
Oh, and as far as MTV:
I take the gay people on "The Real World" with a grain of salt. My friends who are gay, bi, les, etc. show me diversity among individuals, and I definately don't find anything shocking about two guys or two ladies hooking up.
However, MTV's "Real Life: I'm gay, and I'm getting married" or "I'm Coming Out" are interesting and educational, and WILL affect hetero, nontrans and LGBT youth alike. Just seems very straightforward and noncondescending.