What do you mean by "did a video of the modelxmas on my iPad"?
Are you trying to play a video off the Internet? Did you record the video of *your* Model X playing the easter egg? Are you running iMovie on the iPad using video clips that you downloaded from the Internet?
If I had to guess at what you're really asking here, you had your Model X playing the easter egg and you were standing back from it recording video of the action. If this is the case, I would suspect that this is working as designed. Built-in mics are notoriously bad at picking up sound, especially in outdoor situations. For best sound, you should probably have a remote mic plugged into the mic jack. Other than re-recording with a mic closer to the car speakers, I'm pretty sure you could load the video into iMovie on the iPad and then boost the sound level. You may not be too happy with the results since this will also cost the background noise.