http://www.thewrap.com/blossom-flashback-neil-patrick-harris-is-man-of-mayim-bialiks-dreams-in-clip-from-doogie-howser-era-video/

In this flashback clip, Patrick is seen in 1991 at the height of his “Doogie Howser” fame, hobnobbing with Bialik's Blossom in a fantasy episode entitled “Rockumentary.” In the episode, Blossom lies in bed sick and watches rock-themed movies, falling into a hallucination in which she's the most famous rock star in the world.

Harris appeared in the episode as an equally snotty star named Derek Slade, who encourages Blossom to dump her father as her manager.