G159: Providing an alternative for time-based media for video-only content

Refer to “G159: Providing an alternative for time-based media for
video-only content”-
http://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/G159
The first sentence under Description uses ‘an’ before the word ‘video’ but
there is no vowel type sound in 'video.'
Change the sentence to:
The purpose of this technique is to provide an accessible alternative way
of presenting the information in a video-only presentation.

-Devarshi