I tried doing that, it didn't work. Plus, the behavior doesn't fit a device that struggles with many running programs or with the video. I have seen devices that struggled to play videos, the stutter is constant, with the video freezing for a few seconds while sound continues playing and the like. This is not it.
As I said, it really looks like the device is emptying the cache every 30 seconds or so, so it starts downloading the video and playing it, and for a while it works. But then the cache empties, the data is gone, so the Vox can't play a video without data and stop for a second, while the download restarts. That's how it looks like.
And if I play HD videos that are on the device itself, not streaming, there is no problem at all, so it's evidently not the CPU or GPU that screws it up. They're doing fine, it's really a problem of the temporary files used when streaming a video online.
On a different level, I've noticed that if I keep a SD card mounted in the device, it never really goes to sleep and the battery drains relatively quickly, maybe 10% per hour. If I unmount it, the device sleeps well and can take 15 hours to lose 10% battery power.