Implement 'search_videos' in place of 'find_videos_by_text' per Brightcove recommendations

I had more luck with search_videos in brightcove_field_browser_validate(). My impression is that the depreciated 'find_videos_by_text' was either a) skipping the 'name' field from Brightcove or, b) searching the name field far too strictly. I couldn't get video titles to consistently return.

The non-depreciated, oft lauded "search_videos" method saves the say. So let's use it :) Attached patch is for brightcove_field_browser_validate()