YouTube’s HTML5 embed player works great and flawless but why not switch to the old flash player to remind yourself of the good old times when flash ruled 😜. Though YouTube has completely switched to HTML5 based video players, flash players could still be enabled with this simple URL trick or query parameter. This exists to support legacy systems.
Update: This post is obsolete, YouTube no longer supports flash embed player.
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URL Trick (Obsolete)
HTML5: https://www.youtube.com/watch?v=videoID
Flash: https://www.youtube.com/v/videoID
Noticed the difference? All you have to do to load flash player in YouTube is simply replace the watch?v=
with v/
An alternate and simple solution to load flash player is to add the following parameter to youtube URL. Append url with &nohtml5=1
Youtube Flash Player Embed Code (Obsolete)
Like you did in above step, simple replace the embed url with the flash version url. Here is the syntax.
<iframe width="500px" height="294px" src="https://www.youtube.com/v/VIDEO_ID"><iframe>
OR
<iframe width="500px" height="294px" src="https://www.youtube.com/embed/VIDEO_ID?&nohtml5=1"><iframe>
For quick and easy embed I would recommend using youtube embed code generator where you can customize a ton of options like changing youtube embed thumbnail,player technology,etc.