Re: Pictures on message
Welcome to Android Central! Which phone? MMS has a pretty small filesize limit (usually around 1 MB), which is hardly enough to send even a short low-res video. If you want to send a longer HD video, then it's better to upload somewhere like YouTube, your Google+ Photos, or Dropbox, then share the link privately with your friend. That's how Hangouts works when you send a video--it uploads the video to your Google+ Photos, then privately shares the link with the recipient.
The small photos can occur if you're using the messaging app to take the photo, because it may default to a low resolution in order to preserve data (MMS uses your mobile data to send pictures, not your voice signal). If you want to send full sized photos, take it with the Camera app first, then attach the photo to your message.