How to decide "I'll trust this software" for closed-source or precompiled software?
Trust is not a boolean variable, "trusted = true / false", you should better think about trust level.
A few example of questions which may help you to evaluate the trust level you can grant to this software:
- How much do you trust the editor of this software?
- Could the software have been modified by a malicious 3rd-party between being created and being delivered to your computer?
- What is the sensitivity of the data you need provide to this software?
- What is the sensitivity of the data residing on the computer which will run this software?
- How long and how often will need to use this software?
If I correctly understand your question:
- You do not trust the editor, otherwise you wouldn't have asked this question in the first place,
- This software will just need the information related to this webinar you will attend,
- Your computer hosts sensitive or at least personal information which makes you worry about trust issues,
- This will be a one spot usage for this webinar, at best for further reference only.
In such conditions, I would just create some virtual machine so I would not worry anymore with any privacy issue while being free to comply with the webinar requests. Once the webinar ends, I will be free to either archive the VM image or drop it.