There are a two methods you can use to search for a route video.  To zoom in using your mouse wheel until you can see the routes in a particular area and then hover over the route and it will change colour from red to green. Then just click on that route segment route which is now coloured green. If you want to know the name of the route or even its identifier, just hover your mouse pointer at the beginning of the route, which is a small blue triangle. Clicking on a route this way will take you to the beginning of first route segment.

A very fast method is to use the search tool to draw a box around the markers you are interested in and then select an interesting route.

This feature is particularly helpful if there are a large number of routes in a certain area,.  A list of all the routes is presented and you can then choose the route you wish to view.  Just click on the box and then drag the crosshair cursor to place a boundary around the area you want to view.