Suggestions strongly welcomed.
Don't rely on a single tutorial as your sole source of information ...
These things are specified. If you have doubts about the accuracy of a "secondary source" such as a dubious tutorial video, look at the specification.
If reading a specification is too difficult for you1, then look for a reliable tutorial; e.g. for Java-related stuff, look for one written by Oracle.
1 - People who label a specification "obtuse" are probably missing the real point of the specification. A good specification is written with accuracy, precision and completeness as its primary goals. A (so-called) specification that reads like a tutorial is most likely not meeting its primary goals properly.
In this case, the Servlet spec 3.0 (section 14.4.11) makes it clear that you need a servlet-name
element to say what Servlet the matching requests are mapped to.
(You could most likely find the same information in other tutorials, etcetera ...)