Export API and Watchers UserID

I'm trying to export who is watching what issue out of our implementation.

I tried export API http://confluence.jetbrains.com/display/YTD5/Export+All+Issues+from+a+Project and it works nicely. Except that I ran into what seems to be a pretty big obstacle...

Field "WatcherName" shows not a user's login or email but an internal to Youtrack UserID:

<field name="watcherName">
    <value>User: id = 25-39[up-to-date]</value>
    <value>User: id = 25-73[up-to-date]</value>
</field>

I can't find any way to convert those IDs into uses' login names or emails. I tried so far the following APIs and neither can search by UserID:

• http://confluence.jetbrains.com/display/YTD5/Get+User+by+Login+Name
  
• http://confluence.jetbrains.com/display/YTD5/GET+User
  
• http://confluence.jetbrains.com/display/YTD5/GET+Users

Can you please help me to figure out how I can translate these IDs into Login Names or emails?