Changing the NS makes it easier for Sedo to verify your domain I believe.
From their FAQ,
The procedure is as follows:
Enter the domains you want to park into your account by going to ‘Add Domains’ in the My Sedo menu. Please remember to set the relevant category and the domain language for each domain.
Next, go to your registrar (the company where you registered the domains) and change the DNS settings as detailed below.
Primary name server (ns1): ns1.sedoparking.com
Secondary name server (ns2
ns2.sedoparking.com
You may also need the IP addresses for the name servers
Primary name server (ns1): 217.160.95.94
Secondary name server (ns2): 217.160.141.42
Many registrars allow you to carry out a ‘Bulk Edit/Update’ which means you can change the DNS for all of your domains at one go instead of having to do them individually. It can take 1 to 2 days to update the name servers.
Although we recommend changing the DNS servers, it is also possible to forward your domains to our parking system by URL forwarding. This can be done by your registrars – though some registrars charge a fee for this and some do not accept bulk updates for URL forwarding. Should you decide to use this method, please forward the URL to the following address:
http://www.sedoparking.com/domain.com/
Remember to replace ‘domain.com’ with your domain.