Clipping Masks In Photoshop
You can find the create Photoshop clipping mask option in the layer menu but before using it, you need to set up the layers so you have a design to use.
Basic set up
Open an image, duplicate the image layer. Go to the shape tools say a rectangle etc and then create a vector design (use the shape option) and then drag that shape in between the original image and the duplicate. Go back to the duplicate and also go to the layer menu and smart object and convert and then apply an effect such as Gaussian blur and then go to the layer menu and create clipping mask command. You can now see the blur only applied to that part of the design. You can also go to the direct selection tool in the tools panel and manipulate the points of the vector path. Instead of using the duplicated layer as a normal one, you can always convert it to a smart object and it works just as well.
Go to the layers panel and select the layer entry for the effect and then use the bounding box to slightly re-size to trigger a transformation and then you can shift the bounding box around and re-position it over another part of the image and the blurring effect (or any of the other effects or not apply any effects at all) will be applied to that and then press return. To move it again, repeat
Move the contents
You can move it but the actual contents can also be moved, simply click on the clipping mask and drag (without the bounding box to transform etc) appearing and you can then move the contents and re-position the underlying design.
Adding layer effects
It is a vector layer and if you select the vector layer, you can go to the layer menu and select the layer styles and add a bevel as well as drop shadow etc to create all kinds of unique designs.
It is a vector and as such you can edit it using a variety of tools such as the settings in the properties panel if the current selected shape is a rectangle say then you can change the corner settings for the design. You can also tweak the shape of the path by using the direct selection tool and you can select the points and drag the design in all kinds of directions to create all kinds of unique shapes to be used with this feature.
You can also quickly add the same effect (as well as edit it later if you wish) by selecting both the top level image and the effect and converting them into a group via the layer menu and group layers and then use the duplicate layers command and you now have two effects for the price of one and they can be re-positioned across the artwork
Adding a stroke
You can also select the shape and add a stroke to the design. As you are using a vector shape, go to the properties panel or select one of the vector tools and then change the stroke color to black and give it a width of 10pt say as well as adding stroke options such as dashes.
made of multiple designs
You don't have to add just a single path for the effect, you can add multiple designs all over the place by holding down the shift key as you add the paths as they will be added to the current shape and they will in turn be used. Select the top layer and apply the create command found in the layer menu. Add a blur or another effect (if you want an effect, it is not essential) to the top level as well as going back to the shape layer and going to the layer menu and layer style and adding a bevel or shadow etc
The tutorial has had a background, you don't need a background. You can use the effect without the need for any underlying image
Say you don't want the blur or oil paint applied to the shape area, you want it applied to the outside area. A workaround (as there is no invert command) would be to create a shape using the rectangle and the original shape and then use the combine command in the layer menu and subtract and then use that design instead of the original. https://youtu.be/j0bQjuoVVHM
Open an image and then duplicate the layer. Go and select the rectangle (and in the case of this design, make it a very narrow rectangle) or circle etc vector design and then create and then drag that vector design in between the two images. With the original, apply a Gaussian blur or twirl etc. Go to the duplicate and then layer menu and smart object and convert and then go to the layer menu and create command as before. With the smart object and the vector and then drag using the alt / option key and create a duplicate of that the smart object and vector and repeat and create multiples of that combination across the entire image and position as required. Select on the smart object in the pairing and reposition and scale and rotate. You can then build up an image very quickly filled with thin slivers of the image in different positions and frames.