I tried selecting some elements in an HTML document with namespaces, let's say something like that:

var a = $("<a:b><a:c><a:d>hello</a:d></a:c></a:b>");

Now try to do one of these:

$("a\\\\:c a\\\\:d", a);

$("a\\\\:c>a\\\\:d", a);

$("a\\\\:c", a).children("a\\\\:d");

Any of them return any elements.

However, this returns an element with correct children:

$("a\\\\:c", a);

And this also works:

$("a\\\\:c", a).find("a\\\\:d");