Now, once you've got hold of your broom, I want you to mount it. And grip it tight, you don't wanna be sliding off the end.
11 seconds sound clip from the Harry Potter and the Sorcerer's Stone movie soundboard.
You can hear this line at 00:59:17 in the Blu-ray version of the movie.
Quote context
[...]
- When I blow my whistle, I want each of you to kick off from the ground, hard.
- Keep your broom steady, hover for a moment... then lean forward slightly and touch back down.
- On my whistle. Three, two...
[...]