Video recording in Power Point

Hi everybody!!

I am a chemistry teacher uploading videos on chemistry. What I do is, make PPTs then record video on power point and then save the same as mpeg4 video before uploading the same. I purchased a Dell 2in1 (touchscreen) laptop for making it convenient to write and draw on-screen. But I am facing a peculiar problem on this laptop, while recording videos. Whenever I record audio only, it goes perfectly fine, but whenever I record video, the frame rate seems to be very low, and the video moves as if several still photographs are moving to give an abrupt moving video. While sound travels at right pace, the video seems like a number of snapshots moving ahead to give a video look.

I updated all the drivers for the Dell Computer but to no improvement. I contacted Microsoft for improper functioning of power point. They told me to get some add-in to the application to enhance the capability of camera which could solve my problem. Though I offered them to do an unistallation and  reinstallation of the MS Office, but they reluctantly insisted thay I should go for some add-in only. Please advise.