Hi !
So as of now I opted for hiding the title in the webapp builder (i am still in the testing stage so it will work for now). But u can try this..In widgets section click the layers widget and uncheck "Show Title". then enter your desired title in the text box, and if I remember in the youtube video you reference it will cover how to change the styling for that text field so you can customize it to your linking
I have not had the opportunity to test this yet, but my next step was to
1. download the webapp from the appbuilder
2. open Widget.html file
2a. html for me look like so:
<div>
<div class="layers-section" data-dojo-attach-point="layersSection">
<div class="layer-list-title" data-dojo-attach-point="layerListTitle">${nls.layers}</div>
<div class="layer-filter-node" data-dojo-attach-point="layerFilterNode"></div>
<div class="layer-list-body" data-dojo-attach-point="layerListBody">
</div>
</div>
</div>
2b. change ${nls.layers} to my desired title e.g. My Layers
3. Upload/host my webapp and see if it works
not sure if it helped, but hopefully it gave you some ideas of things to try