Many thanks for your patience. It is quite common for the owners of images or videos to aggressively pursue people who use their material in what they believe is without their permission. Often the sums they request are exaggerated and in the hope that people will just pay up in order to avoid further threats or possible legal action. However, in reality the law on copyright infringement is not that simple and the way damages are calculated is different.
If you did download the material in question from a sharing site, then the chances are that copyright would have been infringed. You may not remember the titles in question but if they can show that your IP address linked to your computer was the one which downloaded the material then the chances are that they can prove that you were the one who had downloaded the videos.
Many people simply ignore such threats because the companies do not always pursue matters further. They would have to go to court and win to be able to do anything and ask you to pay anything. Whether you do that is up to you. If you get engaged in correspondence with them and it looks like you admit the allegations, they could use that to try and take matters further.
You say you did not do them out of a sale but obviously you would have had to buy it so there is at least one lost sale there. Also it would depend on whether the software you used, such as file sharing bittorrent that you used to download the movie, shared the files at the same time with others. That is when further damages could be applicable.
If you are to respond, simply deny you eve downloaded these and also remind them that a court will only award actual damages incurred as a result of this, usually limited to the costs one would have paid for the video and overall it would not be worth their time to go that far.
I hope this has answered your query. I would be grateful if you could please take a second to leave a positive rating (3, 4 or 5 stars) as that is an important part of our process and recognises the time I have spent assisting you. If you need me to clarify anything before you go - please get back to me on here and I will assist further as best as I can. Thank you