sizing video in wp video lightbox

i am calling youtube videos with wp video lightbox plugin, all working fine. i can add a size if i use the shortcode, but can’t get the html embed to change size.

url is https://www.seo-usa.org/wordpress2012/media-center/videos#!prettyPhoto

shortcode that works is (which i am not using on that url):

[video_lightbox_youtube video_id=9n7jsfajtC4 width=640 height=400 anchor=https://www.seoscholars.org/wp-content/themes/BuilderChild-seo/images/hpvideolinkimgs1.jpg]

html code that works but displays too small is:

<a href="https://www.youtube.com/watch?v=SCPDbm9JeCg" rel="wp-video-lightbox" title="">#</a>

ways i have tried to change size (these do change the player but then the video comes in really narrow):

<a href="https://www.youtube.com/watch?v=SCPDbm9JeCg" width="640" height="400" rel="wp-video-lightbox" title="">#</a>

<a href="https://www.youtube.com/watch?v=SCPDbm9JeCg" width=640 height=400 rel="wp-video-lightbox" title="">#</a>

<a href="https://www.youtube.com/watch?v=SCPDbm9JeCg width=640 height=400" rel="wp-video-lightbox" title="">#</a>

<a href="https://www.youtube.com/watch?v=SCPDbm9JeCg?width=640height=400" rel="wp-video-lightbox" title="">#</a>

thank you