The other answers should probably do the trick, but this one is simpler and does not require jQuery:
document.head.querySelector("[property~=video][content]").content;
The original question used an RDFa tag with a property=""
attribute. For the normal HTML <meta name="" …>
tags you could use something like:
document.querySelector('meta[name="description"]').content
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…