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