http://eta.health.usf.edu/technology/powerpoint/default_Powerpoint_Tutorial.htm
Mr. Puhitaku developed a software called mtplvcap to "Turn your Nikon camera into a WebCam" at github. Many thanks to Mr. Puhitaku.
https://github.com/puhitaku/mtplvcap
You can download it there. An instruction is also available there. The following is some tip for the users of D7000 and Windows 10.
To execute mtplvcap.exe from the command prompt, change the current directory to the directory in which the mtplvcap.exe exists, and command "mtplvcap -vendor-id 04b0". 04b0 is the vendor id of Nikon.
Open a browser, and go to http://localhost:42839/. Then you will see a video view and its information from D7000 on the browser.
To see the video only, go to http://localhost:42839/view
When I use the video image on OBS at WebEX, horizontally expanded video image appears at WebEX. This must be due to the difference in the aspect ratio at D7000 (3:2) and WebEX. I could distort the image at OBS, so that the image at WebEX appeared to be "normal". I need to check the behavior more before using the D7000 image at the web conferences.