The problem with relying on that approach is that it completely breaks the ability of Martians to use the same internet as Earthlings. There's no getting around the latency problem, but the availability of nearly infinite (over the span of a single 24-hour window of time, from the perspective of any individual user) bandwidth can go a LONG way towards smoothing over the difference by allowing a degree of adhoc websurfing where the user triggers a load operation, then the proxy proceeds to recursively fetch not only that specific page, but every page and bit of content linked to it for several levels. Kind of like getting deliveries on a remote island where it takes weeks for goods to arrive... but when the ship DOES arrive, it's a Chinese-sized mega-freighter that costs almost the same per trip whether it's full or empty.
More importantly, there's a potentially-lucrative market for such local caching services right here on Earth: cruise ships. When a ship's in port, it can have fiber-speed connectivity. When it's at sea, satellite data bandwidth is limited, but hard drive space is cheap. Instead of sending only videos explicitly requested by passengers on a specific ship TO that ship, you could just bundle up all of Youtube's daily updates requested by anyone on any ship that's a customer, and broadcast them once (plus enough extra data for forward error correction) to every ship watching that particular satellite (so that if a passenger goes to watch a video the next day, it'll already be cached locally).
The same approach would work for providing internet access on Antarctica. Run fiber to an island near the Antarctic Peninsula, then build microwave relay towers to handle inland backhaul. Strictly speaking, latency would be low (since it would be microwave to fiber), but bandwidth during the winter would still be scarce because we're talking about a thousand-mile microwave-relay route from the South Pole to the nearest viable fiber drop... and snow does terrible things to link quality above 2GHz (think: weather radar frequencies. The signals hit snowflakes and ricochet & experience doppler shift) during the time of the year when good internet access is needed by residents the most urgently.