If injections don't work for you, I doubt that this exercise program will. Injections force the spongy tissue (corpus cavernosa) to get filled with blood; if it doesn't work, it probably means the blood is flowing back out as it comes in and is not being held there. This is called venous leak.
Most of the experimental work has aimed at restoring vascularization within the corpus cavernosa. Stem cells extracted from fat and injected into the corpus cavernosa have had some success in early trials:
/www.ncbi.nlm.nih.gov/pmc/articles/PMC4816754/There are a couple of clinical trials in the US, in FL and CA:
/clinicaltrials.gov/ct2/show/NCT01953523/clinicaltrials.gov/ct2/show/NCT02087397Another novel approach is the use of low intensity shock waves (it doesn't hurt) to encourage re-vascularization.
www.jurology.com/article/S0022-5347(15)05422-1/abstract/www.ncbi.nlm.nih.gov/pmc/articles/PMC5121537/There are several US clinical trials, but they don't yet allow men who have had a prostatectomy
/clinicaltrials.gov/ct2/show/NCT03039218/clinicaltrials.gov/ct2/show/NCT03067987Outside of a clinical trial, the best known solution is a penile prosthesis.