add support for sandia.gov

[Siddhant]

URL: http://digitalops.sandia.gov/Mediasite/Play/24aace4429fc450fb5b38cdbf424a66e1d

Note that, the viewing experience on the webpage includes slides which change along with the video. Similar to subtitles, maybe we should also think about how to handle slides and information about slides' timings.

[Siddhant]

Looks like they are using the "Mediasite Player" (http://www.sonicfoundry.com/mediasite/player)

[phihag]

youtube-dl 2015.02.19 supports downloading the video, but downloading the slides (or even video + slides) is not supported yet.

[TRox1972]

@yan12125 94a5cff closes this issue also

[yan12125]

Thanks.