Add comprehensive technical research documentation for Beeg video download methods (#1)

* Initial plan

* Add comprehensive Beeg video downloader research documentation

Co-authored-by: devinschumacher <[email protected]>

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: devinschumacher <[email protected]>

Author: Copilot