How to Chose previewType form the extend message

[beshoo]

&proto.WebMessageInfo{
                Key: &proto.MessageKey{
                        FromMe: &fromMe,
                        Id: &ID,
                        RemoteJid: &JID,
                },
                MessageTimestamp: &ts,
                Message: &proto.Message{
                ExtendedTextMessage: &proto.ExtendedTextMessage{
                        MatchedText: &url,
                        CanonicalUrl: &url,
                        Description: &description,
                        Title: &title,
                        Text: &text,
                        JpegThumbnail: thumb,
                        PreviewType : "video", // <=================
                },
                },
                Status: &status,
        }

*cannot use "video" (type string) as type "github.com/Rhymen/go-whatsapp/binary/proto".ExtendedTextMessage_EXTENDED_TEXT_MESSAGE_PREVIEWTYPE in field value**

[beshoo]

proto.ExtendedTextMessage_VIDEO.Enum()