Try 'speedtest.net' to get a check on your download and upload performance. If you just want a one time measure there is no need to register with them, just use the website. If you register, which is free, you can get a record of your connection performance over time and this can be very useful when it comes to arguing with an ISP ! You need to remember that almost all ISPs advertise their services as, for example, upto 10Mbps. If you are on average getting 8 or 9 Mbps, this would be considered quite reasonable. If, again on average, you were only getting 1 or 2Mbps this would probably be regarded as unreasonable although it would literally fit within the description 'upto 10Mbps'.
Your videos may be lagging because of a poor connection, or - if you download a lot - you may be being 'throttled', or you may be suffering purely because of your location relative to the exchange and the number of people in your neighbourhood using the web.
Your web-cam. There is normally a switch somewhere to enable / disable this. It may be a switch mounted beside the lens or it may be a software switch - the 'Fn' key and one of the 'F' keys at the top of your keyboard. I have heard of the seriously paranoid putting a piece of duct tape across the lens !
If you are concerned that unauthorised software is taking images through your web-cam, download and install Malwarebytes, update it then run a quick scan. If it finds any unauthorised software such as malware start a new topic in the 'Am I infected?' section of BC. You can get malwarebytes here :-