Ultimately, it's not something to worry about. Other cameras, like Nikon's D5000, have a limiter that stops recording at five-minutes and both Sony cameras were able to surpass that regardless of settings. We wouldn't be surprised to see Sony apply a similar restriction in a future firmware upgrade to prevent any long-term damage that might result from multiple instances of overheating. Until then, your best bet is to just keep your clips relatively short. And that's true with any HDSLR, all of which will overheat if you run them long enough.