We moved 2019 and 2020 Solution Summits over to the Security Briefings channel here: https://www.brighttalk.com/channel/13159/
They were moved in January so you can scroll down to "4 months ago" and find them there.
If you need anything else, let me know! Happy to help!
I understood @Leonardo1's question to be more about the availability of evidence that he had watched the webinars, rather than access to the webinars themselves.
Given that my BlueSky account no longer works (the site itself is "disabled"), I presume such records are lost in the annals of time. Hopefully, with @AndreaMoore's greater insight, she is able to provide a more positive answer.
On a similar note, do be aware that BrightTalk only keeps your most recent viewing history (IIRC, 10 webinars). Therefore, I recommend keeping parallel records for all auditable activities. For me, this consists of a "CPE Evidence" folder on my PC stuffed with completion certificates.