CENTER VIDEOS

I HAVE HIGHEND THEME….I DON’T UNDERSTAND WHY SUCH A RESPONSIVE SITE WITH SOOO MANY BELLS AND WHISTLES…CANNOT ALIGN ANY VIDEO IN THE CENTER OF A PAGE…….HOW IN THE HELL CAN IT BE DONE???. …I’M TIRED OF SPENDING HOURS ADJUSTING CODES EMBDDING IFRAMES MARGINS, 3 COLUMNS, ETC….AND NOTHING WORKS…..ITS ABSOLUTELY RIDICULOUS THAT I HAVE TO ADD A CUSTOM CSS CODE TO ACCOMPLISH THIS!!!!!!!!!!!!!!! HOW CAN IT BE DONE? EVERYTHING LEFT ALIGNS>>>WHAT CODE IS NEEDED FOR CUSTOM CSS???