Youtube Copyrights

I am a freelancer and my profession is to deliver educational sessions. I used to work with a company where nature of my job was not fixed. I used to get monthly payments in the form of cheque or sometimes in the form of cash. I used to deliver sessions and also manage few other things for them. During my work their, I recorded few of my sessions which I delivered to the students there. Recently I uploaded those sessions on youtube, after few days that company claimed copyrights on one of my video. Youtube deleted that video as per their norms. But, I raised a counter notification for the strike and after 15 days youtube resolved the notification and restored that specific video. I got to know recently that the company has been selling my videos from past 2 years. Now, again that company raised copyright strikes on 4 of my video. My question is, what are my legal options here. I tried contacting youtube on this issue but have received no response from them. Please note that the video was created by me and I am the performer. There are no paper work or any kind of agreement between me and that company for anything.