I agree with Mike, try it in PostMan.  Once you have it working in PostMan, use the same code in the HTTPClient.  You can view what PostMan sends and duplicate it.

I would use postman or snapdevelop's web api tester (under the test menu item) to get the api to work. 

Hi Shenn, the URL format http://username:password@IPAdress/ISAPI/Streaming/channels/1/picture is a special format that uses username and password for Basic Authentication. It is possible that HttpClient doesn't support that format of addressing.  You could try to add the Basic Auth headers yourself and see if that works.

The other thing to be mindful of is that if your password (or username) contains the ~ character, it will need to be escaped.  e.g. if your password was something~secret, you would need to assign it as "something~~secret", not "something~secret".

HttpClient lnv_HttpClient

//Allocate space for the HTTP Client
lnv_HttpClient = Create HttpClient

//Not to read data automatically after sending request (default is true)
lnv_HttpClient.AutoReadData = false

// Using Basic Auth to access the url
// Encode the username:password as a base64 encoded string
string ls_basic
CoderObject lo_Coder

lo_Coder = Create CoderObject
ls_basic = lo_Coder.base64encode( Blob("username:password" , EncodingUTF8!))

// Add the Authorization header
lnv_HttpClient.SetRequestHeader( "Authorization", "Basic " + ls_basic)

// Call the url without the username:password@
lnv_HttpClient.SendRequest("GET", "http://" + is_ip_camera + "/ISAPI/Streaming/channels/1/picture")

"I'm assuming it has to do with passing the username and password at the beginning of the URL instead of at the end."

yes, the url is where to go - sort of like a function name.  Anything after the ? in the url is the arguments for the 'function'.