You can use a cork bark half like she did, silicone it in place or use great stuff foam to hold it in place, then silicone it with the brown silicone. You can silicone aquarium rocks in place. The possibilities are only limited by your imagination. Sorry it took so long to reply to you. Life called. You can run your tubing down behind the background and push it through.

My 20 gallon viv has the tube pushing though the cork bark and down the center of a narrow cork tube so it looks like the water is running out of the tube.