fixing see also links for txt files

[jesgreco]

fixing see also links for add_video.txt

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[jswope00]

I don't think these see also's are thorough enough. Best approach would be to find the navigation section that talks about these tasks, and grab the refs from that.

E.g. for add_html, that is most similar to "Add Text Components" from navigation. Grab those links

[jesgreco]

Changes to the see also tables were made based on navigation files.

[jesgreco]

@jswope00 I think after all my changes this PR is ready for Sarina's review and merge.