About the search field you can search for pattern in clientname, unique Client-ID and Client-database-ID.
You can also use a view filter options (see below). Enter the filter also inside the search field.
Combination of filter and search pattern are possible. Enter first the filter(s) followed without any sign your search pattern.
Also it is possible to combine multiple filters. Enter this consecutively inside the search field.
Example:
filter:nonexcepted:TeamSpeakUser
filter:excepted:
Show only clients, which are excepted (client, servergroup or channel exception).
filter:nonexcepted:
Show only clients, which are not excepted.
filter:online:
Show only clients, which are online.
filter:nononline:
Show only clients, which are not online.
filter:actualgroup:GROUPID:
Show only clients, which are in defined group. Represent the actuel rank/level.
Replace GROUPID with the wished servergroup ID.
filter:country:TS3-COUNTRY-CODE:
Show only clients, which are from defined country.
Replace TS3-COUNTRY-CODE with the wished country.
For list of codes google for ISO 3166-1 alpha-2
filter:lastseen:OPERATOR:TIME:
Show only clients, which are selected by lastseen.
Replace OPERATOR with '<' or '>' or '=' or '!='.
And replace TIME with a timestamp or date with format 'Y-m-d H-i' (example: 2016-06-18 20-25).
Full example: filter:lastseen:<:2016-06-18 20-25:
Level 3 
Level 4