I have the same issue in two of my sites. I perfomed the below mentioned steps in both sites and it resolved the issue of 9971 and jabber for windos video issue one of the sites.
Jabber for Windows introduced Video rate adaption. This allows Jabber to negotiate the optimum video quality based on network conditions. When rate adaption is being used you'll see the client upscale the video experience during the start of the call.
To guarantee an optimal video experience when Jabber is interoperating with your other Video devices you must enabled RTCP on UC manger.Enabling RTCP will allow optimal video adaptation to occur. This is disabled by default and can be enabled in the following way.
On the UC manager administration interface
Select Device/Device Settings/Common Phone Profile (or other profile if you apply a different profile 89/99xx devices)
Confirm the setting for RTCP* is set to enable
This setting can also be overridden in the device specific settings under the "Product specific Configuration Layout"
Again, confirm RTCP* is set to enabled. Note, not all device expose the RTCP setting at a device level.
Settings RTCP to enabled will allow video adaption to take place.
Try it, if this works.