Well, this is really something that has to be decided between you, the buyer and ebay/paypal. Since you have photographs and videos of the condition you sent it in and there was no damage during the transit (evidenced by the intact packaging) then it is your word/evidence vs. that of the buyer with ebay/paypal serving as the arbiter. Your ebay listing shows just one small photo in a bubble wrap, so it doesn't display the condition of the item itself.

It appears at this point you've only gotten a complaint from the buyer and they have not opened a dispute with ebay. If it were me I'd tell them that the item was in the condition described at the time of shipping and if it didn't arrive like this perhaps they can provide you with photographs showing the actual condition. Then your only option is to leave the dispute process play out, if they open a dispute. If that happens ebay/paypal will probably place hold on the funds and take them back out of your bank account if they're there. You would want to talk to ebay on the phone and talk to a real person explaining that you shipped the item as described, you have photographs and videos that show that and the buyer is claiming damage, but there is no evidence of that happened during the shipment.
They'll be able to tell you what are the options you have and how this can be resolved. Their standard policies are in favor of the buyer, but there is also a judgment from real people if necessary.