Ok, done. I wrote a script which safely copied all video URL and placed them in post content as embeds. I cant place here whole code as it contains some company data i work for but least i can do is share some key parts of it.
video URLs are stored in your_wp_prefix_postmeta table in rows meta_value where row meta_key is _video_url. To be sure i joined posts table and filtered those which are posts and are published (wordpress tables are such a mess …).
first query
'SELECT ID,meta_value FROM your_wp_prefix_posts INNER JOIN your_wp_prefix_postmeta ON your_wp_prefix_posts.ID=your_wp_prefix_postmeta.post_id WHERE your_wp_prefix_posts.post_status="publish" AND your_wp_prefix_posts.post_type="post" AND your_wp_prefix_postmeta.meta_key="_video_url" ORDER BY ID'
I striped URLs from meta_values to bare code (https://www.youtube.com/watch?v=CODE => CODE) taking off any additional url parameters and timestamps placed there by mistake and used this CODE to make proper embed code like this
<iframe width=\"720\" height=\"405\" src=\"https://www.youtube.com/embed/'.$CODE.'?feature=oembed\" frameborder=\"0\" allowfullscreen></iframe>
In the same loop i used IDs and those generated CODES to build one single query (didnt want to make many update calls to database) using very simple MySQL syntax.
UPDATE your_wp_prefix_posts SET post_content = CASE ID SET
WHEN '1' THEN 'meta_value_1'
WHEN '2' THEN 'meta_value_2'
WHEN '3' THEN 'meta_value_3'
...
ELSE field_name
END
And it worked. Had double videos now, one from meta fields and one from post content itself. Updated theme and first one dissapeared.
PS. Little advice: before applying the code make some counting of rows you have from first query with mysqli_num_rows() function or other and compare them with actual posts number on your site. Just to be sure that you get proper data.
PS2. Well,ive just noticed that the downside of this operation is that my embeds have fixed width and height and thus they are cropped when are played on small screens. Must to tix that issue too.
