How centering all my embed videos?

@maltrain

Please remove the code I've provided and add the following one, delete all caches and check again:

#wpforo-wrap .wpforo-post-content .wpf-video iframe{
    left: 1%;
}

These are all the css custom codes I have:

#wpforo-wrap {
font-size: 13px; width: 100%; padding: 10px 0; margin:0px;
}
.container.grid-container {
width: 90% !important;
}
body .grid-container {
max-width: 90% !important;
}
.separate-containers .inside-article, .separate-containers .comments-area, .separate-containers .page-header, .separate-containers .paging-navigation, .one-container .site-content, .inside-page-header {
padding: 0px !important;
}
#wpforo-wrap {
padding-top: 0;
}
#wpforo-wrap #wpforo-title{
font-size:2px;
line-height:1px;
position:absolute;
color:#3F51B5;
} 
@media screen and (min-width:900px) {
#wpforo-wrap .wpforo-content {width: 78%;}
#wpforo-wrap .wpforo-right-sidebar{width: 20%;}
}
#wpforo-wrap {
font-family: "Play", Play, sans-serif !important;
}
#wpforo-wrap .wpforo-post-content .wpf-video iframe{
left: 1%;
}

I deleted the cache, CTRL+F5... still nothing.

By the way, I don't know what the first css means, it was there by default when I installed the forum and I don't want to delete it, lol:

#wpforo-wrap {
font-size: 13px; width: 100%; padding: 10px 0; margin:0px;
}