Dale, not that you asked me, but I would offer although that I agree with Marty that your video data files are extremely unlikely to be affected by the re-install, I would verify that the software that you are overlaying is identical to that which is already installed, i.e. version nos, licensing etc, before proceeding. Not that the data files would be touched by the install, but rather if the installed version is actually newer (it happens) than the one you are re-installing, the reinstalled "older" version might not be able to read the "newer" data files format.
I am unsure as to exactly how important the existing data is, but of course if it is critical, I'm sure your syadmin has/will back up the system when possible. Another low risk way of proceeding is to make a new system with a different pc and install Chat there and then copy the files over to the new one and try it. Also maybe there is actually a default password that you will see when you install on a new one. In any case take note of what constitutes a valid password for the next step. Also you can nose around the new install (if you feel comfortable doing so) to find an .ini fille or reg file that might have clear text passwords.
Finally since you know the login name (admin) you are after, here is a list of the 25 most commonly used passwords
1. 123456
2. password
3. 12345678
4. qwerty
5. abc123
6. 123456789
7. 111111
8. 1234567
9. iloveyou
10. adobe123
11. 123123
12. admin
13. 1234567890
14. letmein
15. photoshop
16. 1234
17. monkey
18. shadow
19. sunshine
20. 12345
21. password1
22. princess
23. azerty
24. trustno1
25. 000000