This is the theme song of Scooby-Doo! Trapped.
"Oh we're trapped!"
It shows Scooby running away from a demon.
It shows Shaggy running from a dryad.
"Yes we're trapped!"
It shows Fred, Daphne and Velma running from a phantom.
"C'mon Scooby you can escape!"
"Yes you can!"
It shows Scooby running from the phantom. Fred tosses a net on the demon.
It shows Shaggy running from the dryad and the phantom. Fred tosses a net on the monsters.
They are unmasked, the phantom is an old man, the dryad is a young woman, and the demon is Scooby.
"Oh Scooby-Doo Trapped!"
It shows the series titlecard and then the episode titlecard.