First, you can specify a second category in a video article if you wish and just enter a comma-separated list of categories in the "Widgets" tab field.
The problem with the two URLs you have given above is that they are both pointing to the "utube-gallery" section. This section and the one for the Vimeo gallery are specifically for the galleries.
You need to place your video articles in another section. In my demo they are in the "articles" section but you can create special sections for them if you wish. Once that is done the link to the individual video will include the section that you have attached it to so for example, if you used the "articles" section as I have done in the demo the link would point to http://gps.punctedeinteres.ro/articles/ … spirit-500
You will need to enter your section names in the "Widgets" tab.