4K Resolution

Does anyone know if it's possible to record video at 4K in Xonotic on a 1080p monitor?

I have a 970m GPU. I was wondering if it's possible on the 970/980 GPU line of cards, or if there's a setting that can be used to allow this?

It might be possible in window mode. Game window will obviously stretch out of your monitor(s), but it will probably render AVIs just fine.

I tried this by recording 1920x1080 footage on a 1600x900 monitor. Fullscreen footage version looked all poopy and glitchy, but window mode was all fine.