Search is a basic function that can be found in the top middle. You can write for any media that you wish in search and press "Enter". In this example the search term is "excel"
The result will display all the media, playlist, that have the text "excel" in the title, descriptions, tags or in any custom fields.
If you have a lot of content in the media libray, you may have to filter the search more extensively. In this case you should click on "expand advanced search".
In Advanced search you are offered additional search functions such as "created from-to", "updated from to", "Tags"
You can also create an "Smart filter" by chosing clicking "Save As" and continue by giving it a name. The filter will appear in the left navigation bar under search filters.