This is the actual answer. Just post it here for next users:
Actually, it seems that current implementations don’t rely on the
capture attribute at all, but only on the type and accept attributes:
the browser displays a dialog box in which the user can choose where
the file has to be taken, and thecapture
attribute is not taken
into consideration. For example, iOS Safari relies on the accept
attribute (not capture) for images and videos (not audio). Even if you
don’t use theaccept
attribute, the browser will let you choose
between “Take Photo or Video” and “Choose Existing” (thanks to@firt
for pointing this out).
From this
EDITED 17 Feb 2016:
This behavior is still active on devices.