In order to do this you need to firstly find the video you wish to download from Viki which can be done by searching through the 'channels' or do a direct search for a specific show. Once you've found the show you want to download you should open it up in a separate window. You need to keep in mind that a show is usually split into three or six parts depending on the length, so if you open them up altogether then you have a better chance of keeping track of them.
After that you should access www.clipnabber.com and go to the top of the screen where you will find a box where you can paste in links. You should go back to the first part of the video you want to download and paste the link into the box on clipgrabber. Once you've done that wait until the website has processed the link. When it is ready you should be able to click on the 'download' link and save the video in an appropriate location on your computer. Continue this process for all the sections of the show you want to download.
Once you've saved the whole episode you should import all the clips into a video editing program which could be Adobe Premiere or Windows Media Player. Make sure you put the sections into the right order and then go on to render the full video and save it.