The payment gateway BitPay calculates how many bitcoins equal a USD price and then give that amount (minus their fee) in USD to Namecheap within 2 days.
"It does not matter how many bitcoins we collect, how long it takes to collect them, what we can sell them for, or how long it takes to sell them."
If the seller and the payment provider quickly convert their bitcoins into USD -- as seems likely to be the case based on the link in Maxious's reply -- then they're minimizing the time interval during which their wealth is exposed to exchange rate fluctuations.
Well every currency is volatile isn't it? I guess (if namecheap is a us-based company) they're bitcoin price would fluctuate just as the bitcoin does in relation to the usd.
What if bitcoin drops and I fill register domains on the cheap? Is there a way to prevent this? Are the prices somehow pegged to the dollar?