Hi Sivakumaran,
There are a couple of ways of doing this.
- take a frame, add your watermark to it, save that frame, repeat the process for all your frames, or the particular ones you want to water mark.
To achieve this there are a couple of ways: - use Image Processing and write a for loop, to get each frame, and add your watermark
OR if you have the Computer Vision System Toolbox, I would invite you to explore System Objects. Use the help and you will see that this makes life easy controlling the frame indexing.
There is an example on MATLAB central with free code for you to check out: http://www.mathworks.nl/matlabcentral/fileexchange/28410-watermark-project-watermarking
Please note that this has come up in other threads: http://www.mathworks.nl/matlabcentral/answers/114365-how-can-i-programming-of-digital-watermark
I hope this helps. Gareth