[1/2] A logo of Tencent is seen at its booth at the 2020 China International Fair for Trade in Services (CIFTIS) in Beijing, China September 4, 2020. REUTERS/Tingshu Wang BEIJING, April 7 (Reuters) - Douyin, the Chinese counterpart of TikTok, and internet giant Tencent (0700.HK) have agreed to explore the joint promotion of short and long videos, in a thawing of frosty relations that has often been marked by lawsuits and public spats. Douyin, which like TikTok is owned by ByteDance, said in a statement it is now authorised to use Tencent Video content and rules about how secondary content...