How to access to CCTV with a router that doesn't support DDNS

The MikroTik certainly supports DynDNS updates - I know because that's what I use.

You'll find a number of good scripts in their forums and Wiki, depending on what version of RouterOS you're running. On RouterOS v4 I'm using the following:

# User configuration follows
:global ddnsuser "yourUSERNAME"
:global ddnspass "yourPASSWORD"
:global ddnshost "yourHOSTNAME.dyndns.example"


# Do not edit below this line
:global ddnsinterface "WAN"
:global ddnssystem ("mt-" . [/system package get [/system package find name=system] version] )
:global ddnsip [ /ip address get [/ip address find interface=$ddnsinterface] address ]
:global ddnsip [:pick $ddnsip 0 [:find $ddnsip "/"] ]
:global ddnslastip

:if ([:len [/interface find name=$ddnsinterface]] = 0 ) do={ :log info "system No interface named $ddnsinterface, please check configuration." }
:if ([ :typeof $ddnslastip ] = "nothing" ) do={ :global ddnslastip  [/file get dyndns.txt contents] }
:if ([ :typeof $ddnsip ] = "nothing" ) do={

:log info ("system No ip address present on" . $ddnsinterface)

} else={

# We have a WAN IP, do update

  :if ($ddnsip != $ddnslastip) do={

    :log info ("system Sending UPDATE for " . $ddnshost . " from " . $ddnslastip . " to " . $ddnsip)
    /tool fetch user=$ddnsuser password=$ddnspass mode=http address="members.dyndns.org" src-path="/nic/update?hostname=$ddnshost&myip=$ddnsip" keep-result=no
    :global ddnslastip $ddnsip

# Log current IP
/file set dyndns.txt contents="$ddnsip"

  } else={ 

    :log debug "system No changes necessary."

  }

:log debug "system Update process complete"

}

Note that it doesn't handle the inactivity timeout, since I have a paid account and it doesn't matter to me. Adding that however should be pretty easy.

Edit

Most routers expect to be the WAN connected device, so will generally fail to update correctly. If you were to use a router running DD-WRT then you'd probably be ok, since it's default client uses web based detection.