udpate to the videos section blockstack/blockstack.org#499

[guylepage3]

Update to the videos from https://github.com/blockstack/blockstack.org/issues/484

[CLAassistant]

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[guylepage3]

@yknl can you please merge this in when you get a moment? This is for the updates to blockstack.org that @muneeb-ali @shea256 have requested. Thank you sir.

[yknl]

Merged and updated blockstack.org

[guylepage3]

Thank you sir. 👍