[BiteCode_dev]

Good memory.

But very platform dependant, so maybe OP is on a browser or OS that doesn't let you do that.

I know it works on Chrome for me, but not on FF.

[capitainenemo]

Probably because firefox has alt+(left|right)arrow as global navigation bindings, and is capturing them before the captcha can get them. requesting a fullscreen gaming mode avoids more key binding issues, but probably ruins the "captcha" feel.