There are many factors that determine if a thumbnail preview image appears on a mobile device when a Dubb video url is sent. These include;
- whether you in the person's contact list already
- whether you are on an Android or iPhone mobile device
- whether they have clicked a link from an SMS received from you in the past.
It is very difficult to say with certainty since there are also security protocols based on the mobile carrier. A work around that we recommend is to download a thumbnail image from the video info page and send that as a separate SMS message. Please note: We do NOT recommend sending a text message with an image in the same message (in case the image does not get sent).