- But, like, what happened to our mysterious professor?
- Well, if he was driving this truck, he's disappeared.

7 seconds sound clip from Scooby-Doo, Where Are You! - What a Night for a Knight (S1E1).

You can hear this line at 00:04:00.909 in the Blu-ray version of the episode.

Quote context

[...]

- Hyde White?

- I've heard of hide-and-seek before, but I've never heard of Hyde White.

- That's an English name, you comedians.

- Hey, what's this? It's a delivery label that says, Deliver to the County Museum.

- So that's where the old knight was headed for.

- That's using the old noodle.

- But, like, what happened to our mysterious professor?

- Well, if he was driving this truck, he's disappeared.

- Well, gang, it looks like we're up to our armor-plates in another mystery.

- Oh, dear, oh, dear. I suppose I should thank you for finding the Black Knight, but with Professor Hyde White's mysterious disappearance and all, I wish you hadn't.

- Why is that, Mr. Wickles?

- Because of the legend.

- Legend?

- Yes. The Black Knight is supposed to come alive when the moon is full.

[...]