Does earning money for uploading educational files online, with the intention of seeking reward from Allah and benefiting people, deprive one of divine reward? And is the sound at the beginning of the attached video considered music?

Receiving material compensation for uploading files and spreading knowledge does not negate good intentions and seeking reward from Allah, for seeking worldly gain does not prevent seeking reward in the Hereafter. The evidence for this is the Almighty's saying: "{There is no blame upon you for seeking bounty from your Lord}," and the Prophet's (peace be upon him) statement before battle: "Whoever kills a combatant shall have his spoils." And taking a fee for memorizing the Holy Quran does not contradict receiving reward and recompense from Allah if the intention is sincere.