I have exacly the same issue. i dont know if local ipfs will help, being dtube decentralized plataform...or just changing the gateway sometimes helps.
For files to upload i normaly use mp4 and dont have problems...
i wich there was a blog/community for dtube.. they should have a better FAQ, support or even a simple chatbot to help new users to dsolve some simple problems and to promote the plataform... i believe a good steemit wiki, explaining all plataform would help promote steem