Here is the code I used and added this to my html css file.
/* This is on the timeline on profiles etc for the url scanner youtube videos */
/* yt player in the action link on timeline */
@media only screen and (max-width:501px){
#profile .action_item_link iframe{ width:100%!important;height:198px!important;display:flex;margin:auto}}
@media only screen and ( min-width:501px )and ( max-width:587px){
#profile .action_item_link iframe{ width:440px!important;height:248px!important;box-shadow:2px 4px 6px rgba(0,0,0,0.8);display:flex;margin:auto}}
@media only screen and ( min-width:587px )and (max-width:998px){
#profile .action_item_link iframe{ width:420px!important;height:237px!important;box-shadow:2px 4px 6px rgba(0,0,0,0.8);display:flex;margin:auto}}
@media only screen and ( min-width:998px )and (max-width:1100px){
#profile .action_item_link iframe{ width:520px!important;height:293px!important;box-shadow:2px 4px 6px rgba(0,0,0,0.8);}}
@media only screen and ( min-width:1110px ){
#profile .action_item_link iframe{ width:640px!important;height:360px!important;box-shadow:2px 4px 6px rgba(0,0,0,0.8);}}
And here is the link to my site profile where the top three posts in the timeline are videos so click on the link and you will see the videos show up with the styling above.
http://1940snetwork.com/founder
Regards
John

updated by @john-bizley: 01/08/15 06:30:31AM