1 - write a better XSL stylesheet? I am not an XSL expert.
2 - evaluate the use of the <ttl/> RSS element.
3 - use the <enclosure/> element for pump.io media objects
4 - use the <enclosure/> element for images on dilbert.com
5 - show cards directly in RSS items for twitter.com
6 - show direct links for videos in the Instagram feed
7 - check the encoding of the tweets when UTF is used,
8 maybe solvable with mb_convert_encoding()?
9 See http://php.net/manual/en/domdocument.loadhtml.php